Diese Dissertation umfasst drei Aufsätze zu Mindestlöhnen, zum Arbeitsangebot sowie zu öffentlichen Finanzen. Der Fokus liegt auf den Entwicklungen in Deutschland innerhalb der letzten zwei Jahrzehnte. Der erste Aufsatz untersucht Beschäftigungseffekte des Mindestlohns in einem Modell der Sucharbeitslosigkeit. Das Modell bildet Heterogenität auf Arbeitnehmer- und Arbeitgeberseite ab und schränkt die Richtung der Beschäftigungseffekte ein. Es erlaubt eine unterschiedliche Frequenz der Stellensuche von Beschäftigten und Arbeitslosen und modelliert die Rekrutierungsintensität der Unternehmen. Die Ergebnisse zeigen, dass die Arbeitslosigkeit eine nicht-monotone Funktion des Mindestlohns ist. Die Auswirkungen von verschiedenen Mindestlöhnen unterscheiden sich stark nach Arbeitsmarktsegmenten. Der zweite Aufsatz befasst sich mit Trends im Arbeitsangebotsverhalten in Deutschland. Dazu werden diskrete Wahlmodelle des Arbeitsangebots für die Jahre von 1998 bis 2018 geschätzt. Die implizierten Arbeitsangebotselastizitäten haben in den letzten zwei Jahrzehnten zugenommen, insbesondere für Paare und für alleinstehende Männer. Eine Zerlegungsanalyse zeigt, dass Veränderungen in der Demografie nur eine geringe Rolle bei der Verschiebung der Eigen- und Kreuzlohnelastizitäten von Männern spielen, da der größte Teil der Veränderungen durch Präferenzen oder Arbeitsmarktrestriktionen bedingt ist. Bei Frauen hingegen spielen demografische Veränderungen eine größere Rolle für den Anstieg der Elastizitäten. Der dritte Aufsatz befasst sich mit den deutschen Staatsfinanzen sowie mit Reformen aufgrund der Finanzkrise 2008/2009. Der Aufsatz stellt die makroökonomische Situation und die Entwicklung der Krise in Deutschland dar und beleuchtet die Bedeutung für die öffentlichen Finanzen. In dem Aufsatz werden zudem die Verteilungswirkungen der Reformen im Steuer- und Transfersystem mithilfe von Mikrosimulationen untersucht. / This dissertation consists of three essays on the minimum wage, labour supply, and public finances. The selected essays focus on the German experience and developments over the last two decades. The first essay is an analysis of unemployment effects of the German minimum wage in an empirical equilibrium job search model. The estimated model with worker and firm heterogeneity does not restrict the sign of employment effects a priori; it allows for different job offer arrival rates for the employed and the unemployed and lets firms optimally choose their recruiting intensity. Results show that unemployment is a non-monotonic function of the minimum wage level, and effects differ strongly by labour market segment. The second essay is on the topic of labour supply elasticities in Germany. In order to analyse recent trends in labour supply in Germany, a static discrete choice model of unitary household labour supply is estimated for each year 1998 to 2018. Findings are that own-wage labour supply elasticities implied by the models have increased over the last two decades, especially for couples, and for single males. A decomposition analysis shows that compositional changes in demographics play only a minor role in the shift in males' own- and cross-wage elasticities, since most of the changes in elasticities are driven by preferences or labour market restrictions. For females, changes in composition play a bigger role in the rise of elasticities. The third essay reviews German public finances through the financial crisis 2008/2009. The essay starts with a presentation of the macroeconomic situation and how the crisis unfolded in Germany, before focusing on the situation of the public finances. Finally, the distributional effects of policy responses to the financial crisis are analysed on the individual level using microsimulation.

The <u>first essay</u> [“Twin Deficits and Free Lunches: Macroeconomic Outcomes In Anticipation of Foreign Aid”] concerns itself with situations in which private agents anticipate a future windfall (free lunch) that will help service the debt resulting from a present fiscal expansion (implemented via a temporary tax cut). Such expectations of a windfall can arise in the context of natural resource discoveries or, more interestingly, due to perceptions by agents in “too important to fail” countries that will be bailed out through higher foreign aid or debt relief. We employ an overlapping generations model featuring credit constraints to study the real effects of such free lunch expectations in a small open economy, drawing contrasts with the standard tax and money finance closure rules. The model is solved analytically and shows that anticipated aid is equivalent to current aid when agents have perfect foresight, so that a temporary tax cut is seen as permanent. Accordingly, agents raise their consumption and indebtedness (at the expense of future generations) by an amount that is an increasing function of their “impatience” (subjective rates of time preference plus probability of death). A worsening of the current account obtains (twin deficits) across a range of plausible closure rules, including those featuring money finance. The introduction of credit constrained households (we study the variant where myopic agents spend their current disposable incomes) does not alter the basic result in the case of full aid finance, but does matter for mixed tax-aid regimes, in more complex settings where agent expectations and donor promises on aid diverge, and when governments face borrowing constraints so that the timing of aid delivery matters. The <u>second essay</u> [“The Role of Domestic Debt in Economic Growth: An Empirical Investigation For Developing Economies”] focuses on the remaining source of government financing, i.e. domestic debt, and the role it can play in mobilizing private savings, facilitating credit intermediation in higher risk settings (i.e. serving a “collateral” function on bank balance sheets), developing financial markets and supporting economic growth in general. To investigate this question empirically, we set up a new domestic debt database covering about 100 developing economies, going back three decades to 1975; explore Granger causality links between domestic debt and key macroeconomic and institutional variables; and estimate the growth impact of domestic debt using panel regressions, allowing for non-linear effects. Domestic debt, as a share of GDP is found to exert a significant positive impact on economic growth, with potential channels including domestic savings mobilization, provision of risk-insurance on banks’ balance sheets; and greater institutional accountability of the state to its citizens. Although this result countervails more established arguments against domestic debt (i.e. that it leads to crowding out and banks to become lazy), there is some evidence that above a ratio of 35 percent of bank deposits, domestic debt does begin to undermine economic growth. The growth payoff also depends on debt quality, with higher payoffs observed for positive interest-rate bearing marketable debt issued to nonbank sectors. The <u>third and final essay</u> [“Why Do Banks in Developing Economies Hold Domestic Government Securities?”] explores demand-side determinants of domestic debt, by focusing on commercial bank holdings of government paper, discriminating carefully between voluntary factors (such as mean-variance portfolio optimization) and statutory ones (cash reserve and capital adequacy requirements). The analysis is made possible by the construction of a dataset on government and private returns (real and nominal) for almost 600 banks from 70 emerging and low-income economies, spanning the (pre-Basel II) period 1995-2005. A battery of structural cross-section regressions indicates that banks’ portfolio decisions are at least as significantly influenced by mean-variance considerations as regulatory factors: the actual portfolio share of government securities (λ) responds intuitively, and sizably, to variations in the moments of the distributions for government and private returns as well as in the minimum-variance portfolio share (λ*). Higher cash reserve requirements tilt portfolios away from government securities toward riskier private lending, while higher capital adequacy requirements work the other way. The association between actual portfolios and the identified determinants is noticeably weaker at lower ends of the λ distribution, suggesting the domination of non-CAPM factors in those contexts.

La problématique du financement du développement dans les pays en développement se trouve au coeur de cette thèse. Cette dernière s'articule autour de quatre chapitres sur les questions liées au financement du développement. Le chapitre 1 explore les effets des épisodes budgétaires dans les principaux pays donateurs principaux de l'OCDE (Organisation pour la Coopération et le Développement Economique) sur leur offre d'aide au développement aux pays en développement. On observe que les épisodes budgétaires affectent significativement l'offre d'aide, avec une différence comportementale en termes d'offre d'aide du groupe de pays de l'Union européenne versus le groupe de pays de l'OCDE n'appartenant pas à L'Union européenne. Le chapitre 2 s'intéresse aux conséquences des transferts des migrants et de l'imprévisibilité de l'aide au développement sur la probabilité de consolidation budgétaire dans les pays en développement. Les résultats montrent que les transferts des migrants affectent positivement et significativement cette probabilité alors que l'effet est statistiquement nul pour l'imprévisibilité de l'aide. Ces résultats suggèrent en l'occurrence qu'une meilleure gestion des recettes issues de ces transferts durant les périodes de boom économique pourrait aider à éviter de telles situations et offrir une marge de manoeuvre plus importante à ces gouvernements pour la mise en oeuvre de politiques contra-cycliques pendant les périodes de basse conjoncture. Le chapitre 3 analyse l'existence ou non d'effet de la vulnérabilité structurelle des pays en développement sur leur dette publique totale. Les résultats suggèrent qu'un tel effet existe : en l'occurrence, on montre l'existence d'une relation en forme de 'U' entre la vulnérabilité structurelle de ces pays et leur dette publique totale. En focalisant dans le chapitre 4 sur les pays de la zone Franc CFA, nous examinons si leur vulnérabilité structurelle conduit les gouvernements à un endettement excessif. Les résultats suggèrent que plus ces pays sont vulnérables, plus ils sont enclins à un endettement excessif et qu'au-delà d'un seuil de vulnérabilité, leur probabilité d'endettement excessif diminue. Ces résultats obtenus aussi bien pour l'ensemble des pays en développement que pour les pays de la zone Franc CFA suggère que les Institutions Internationales telles que la Banque Mondiale et le Fonds Monétaire International (FMI) devront prendre en compte cette vulnérabilité dans l'évaluation des politiques de développement ainsi que leurs recommandations – en particulier sur les questions liées à l'endettement – pour ces pays. / The issue of financing development in developing countries is at the heart of this thesis. The latter revolves around four chapters on financing development related matters. The chapter 1 explores how fiscal episodes in the main traditional OECD (Organization for Economic Cooperation and Development) donors affect their supply of development aid towards developing countries. Evidence is shown that fiscal episodes affect significantly aid supply, with a behavioural difference between European Union and Non-European countries in terms of aid supply. The chapter 2 deals with the consequences of development aid unpredictability and migrants' remittances on fiscal consolidation in developing countries. We find evidence that while migrants' remittances exert a positive and significant effect on the likelihood of fiscal consolidation in developing countries, development aid unpredictability does not. These results particularly suggest that a better management of the revenues derived from these private transfers during their booms could help avoid such situations and allow greater room of maneuver for governments’ recipients to implement countercyclical measures during bad times. The chapter 3 investigates whether the structural vulnerability of developing countries matters for their public indebtedness and evidence is obtained that it does. More specifically, we observe the existence of U-curve relationship between this structural vulnerability and the total public debt of these countries. Focusing on the specific case of CFA Franc Zone countries in chapter 4, we examine the relationship between the structural vulnerability and the probability of entering into excessive public debt. We also obtain evidence of a nonlinear effect of the structural vulnerability indicator with respect to the probability of entering into excessive debt: a rise in the structural vulnerability of these countries increases their probability to engage into excessive debt; however this probability declines after a certain threshold of their structural vulnerability. These results (both for developing countries and particularly for CFA Franc Zone countries) suggest that international development institutions such as the World Bank and International Monetary Fund (IMF) should take into account such vulnerability in their assessment of the adequate development policies and recommendations - especially those related to debt issues -, to these countries.

有鑑於歐洲各國的福利政策與福利支出相較於其他國家高，歐洲國家多會提供窮困與殘障的人民最基本的社會保障，一般人民亦可享受到基礎醫療保障，在失業時也可以領取失業補助；歐洲各政府甚至會收購即將倒閉的企業或者提供補助使企業能夠繼續經營。然而在持續延燒的歐債危機下，為維持歐元區普遍的薪資和福利水平，歐元區內國家開始採取了國家借貸的做法，但由於國際經濟形勢不佳，歐元區經濟增量未達預期，許多國家原有債券陸續到期，若無法借到新貸款，國家將面臨倒閉危機。因此本論文主要以動態隨機一般均衡模型(DSGE)，探討一個封閉經濟體系下，政府支出進入家計單位效用函數後，換言之政府支出變動將會影響家計單位消費的邊際效用，試著尋找能夠極大化社會福利的政府公債占國內生產毛額的最適比例。我們發現在提高政府公債占國內生產毛額比例時：家計單位將預期未來稅賦繳納之金額更高，因而減少消費、增加儲蓄，所以會排擠掉部分私人消費；同時政府必須提撥部分費用以支付債券利息，所以將排擠掉部分政府支出。另外隨政府公債占國內生產毛額比率上升，整體社會福利水準會逐漸下降；因此，我們認為最適政府公債占國內生產毛額比率應為零。 關鍵字：動態隨機一般均衡模型、政府支出、邊際效用、公債、國內生產毛額、社會福利水準 / In Euro zone, large spending obligations needed to support the welfare state and redistribute wealth in an effort to gain greater equality. Most European countries provide liberal social security benefits to the poor, disabled, basic medical needs and very liberal unemployment benefits. They also own and run large public companies. Under the ongoing Euro debt crisis, European governments figure out the way to maintain the high welfare level by increasing the public debt they hold. In our paper, we would like to investigate the optimal ratio of public debt to GDP by constructing a micro-based dynamic stochastic general equilibrium model (DSGE) under a closed economy. We focus on discussing the optimal ratio of public debt to GDP which maximizes social welfare in economy while putting the government expenditure into households’ utility. That is to say, the government expenditure will influence the marginal utilities of households. We find out that as a government decides to raise the debt to GDP ratio; it will crowd out both private consumption and government expenditure. Because households will expect to pay more tax in the future, they will decrease their consumption and increase their saving; high debt ratio means government should have paid more interest payment in the future. Also as the ratio of public debt to GDP rises, the social welfare becomes lower. Thus, in our findings, the optimal debt ratio to GDP should be 0. Keywords: DSGE, Government expenditure, Marginal utility, Public debt, GDP, Social welfare

L'objectiu d'aquesta tesi és analitzar com s'han de concebre les polítiques fiscals i monetàries en un context en què els polítics tenen problemes de credibilitat. Es desenvolupen metodologies i aplicacions per mostrar com diferents graus de credibilitat de les institucions polítiques afecten la determinació d'impostos, deute públic, instruments monetaris i, en general, els resultats econòmics. En el primer capítol - Loose commitment (Compromís Dèbil) -, s'introdueix una nova metodologia per resoldre problemes de política òptima tenint en compte que els polítics podrien no complir les seves promeses, i analitza els efectes de la credibilitat sobre la imposició sobre el capital i sobre el treball. El segon capítol - Political Disagreement Lack of Commitment and the Level of Debt (Desacord Polític, Falta de Compromís i el Nivell de Deute) - considera un cas en què la credibilitat es limitada per el fet d'haver-hi alternança entre polítics amb objectius diferents. En particular, es mostra com l'alternança política i la falta de compromís afecten el nivell de deute públic. Finalment, el tercer capítol - The Macroeconomic Effects of Unstable Monetary Policy Objectives (Els Efectes Macroeconòmics de la Inestabilitat dels Objectius de Política Monetària) - analitza com la possibilitat de canvis en els objectius influeixen en les decisions de política monetària. / El objetivo de esta tesis es analizar cómo se deben concebir las políticas fiscales y monetarias en un contexto en que los políticos tienen problemas de credibilidad. Se desarrollan metodologías y aplicaciones para mostrar cómo diferentes grados de credibilidad de las instituciones políticas afectan la determinación de impuestos, deuda pública, instrumentos monetarios y, en general, los resultados económicos. En el primer capítulo - Loose commitment (Compromiso Débil)-, se introduce una nueva metodología para resolver problemas de política óptima tomando en cuenta que los políticos podrían no cumplir con sus promesas, y analiza los efectos de la credibilidad sobre la imposición sobre el capital y el trabajo. El segundo capítulo - Political Disagreement Lack of Commitment and the Level of Debt (Desacuerdo Político, Falta de Compromiso y el Nivel de Deuda) - considera un caso en que la credibilidad está limitada por el hecho de que hay alternancia entre políticos con distintos objetivos. En particular, se muestra cómo la alternancia política y la falta de compromiso afectan el nivel de deuda pública. Por último, el tercer capítulo - The Macroeconomic Effects of Unstable Monetary Policy Objectives (Los Efectos Macroeconómicos de la Inestabilidad de los Objetivos de Política Monetaria) - analiza cómo la posibilidad de cambios en los objetivos influye en las decisiones de política monetaria. / The purpose of this thesis is to analyze how fiscal and monetary policies should be designed in a context where policymakers have credibility problems. Methodologies and applications are developed to show how different degrees of policymakers' credibility affect the determination of policy choices, such as taxes or monetary instruments, and more generally the economic outcomes.The first chapter - Loose Commitment -, introduces a new methodology to solve optimal policy problems taking into account that policymakers may not fulfill their promises, and analyzes the effects of policymakers' commitment on capital and labor taxation. The second chapter - Political Disagreement, Lack of Commitment and the Level of Debt - considers a case where commitment is limited by the fact that policymakers with different objectives alternate in office. In particular, it is shown how lack of commitment and political turnover affect the level of public debt. Finally, the third chapter - The Macroeconomic Effects of Unstable Monetary Policy Objectives - analyzes how the possibility of changes in policy objectives influences monetary policy choices.

Cette thèse s’intéresse d’une part aux effets macroéconomiques des régimes de change, et d’autre part, aux récentes évolutions sur la politique budgétaire et la décentralisation. La partie I met essentiellement l’accent sur l’interaction entre les régimes de change (RC) et la politique budgétaire, monétaire et fiscale. Tout d’abord, nous mettons en évidence que les RC peuvent avoir un effet stabilisateur sur la politique budgétaire (chapitre 1). Cependant, cet effet stabilisateur des RC n’est pas automatique mais dépendrait plutôt des conséquences d’une politique budgétaire laxiste. Le chapitre 2 s’intéresse quant à lui à la causalité entre RC et crises (bancaire/financière, de change et de dette) et remet en cause la vision bipolaire qui prétendait que les RC intermédiaires sont plus vulnérables aux crises que les solutions en coin (RC fixes/flexibles). Il ressort de notre analyse que les fondamentaux macroéconomiques (la volatilité du crédit au secteur privé, le financement du déficit, et le ratio dette sur PIB) jouent un rôle considérable. Le chapitre 3 met en évidence un lien entre les RC et la politique fiscale. Les pays à RC fixes montrent une plus grande dépendance aux recettes domestiques –telles que la TVA-, comparativement aux pays en change intermédiaires/flexibles pour compenser les pertes de recettes de seigneuriage (effet de substitution). De plus, ces pays avec RC fixes collectent plus de recettes domestiques en compensation de la perte de recettes douanières, suite à la libéralisation commerciale (effet de compétitivité). Dans les trois derniers chapitres (partie II), nous mettons le focus sur la politique budgétaire et les effets de la décentralisation. Le chapitre 4 révèle une relation non-linéaire entre la politique budgétaire et le cycle économique, qui dépend du niveau de la dette publique. Lorsque celle-ci dépasse un certain seuil (87%), la politique budgétaire perd toute propriété contra-cyclique. Nous montrons par ailleurs que l’effet disciplinaire ex-ante des règles budgétaires aide à restaurer la contra-cyclicité de la politique budgétaire. A travers le chapitre 5, nous montrons que la décentralisation budgétaire, dans un cadre politico-institutionnel sein et dépourvu de corruption, améliore l’offre de biens et services publics. Le chapitre 6 conclut que la décentralisation impacte positivement le solde structurel. Cependant une asymétrie entre la décentralisation des dépenses et celle des recettes accroit la dépendance des gouvernements locaux vis-à-vis du gouvernement central en termes de transferts, et amoindrirait considérablement à l’effet positif de la décentralisation. / This thesis explored, in two parts, the macroeconomic impacts of exchange rate regimes (ERR), as well as the recent developments in fiscal policy and fiscal decentralization. Part I has reconsidered the role of ERR and its interplay with fiscal, monetary and tax policy. The first result that emerges (Chapter 1) is that fixed ERR can serve as a credible policy tool for stabilizing fiscal policy. However, this stabilizing effect is conditional upon the inter-temporal distribution of the costs of loose fiscal policy. In assessing the linkage between ERR and crises (banking/financial, currency and debt), Chapter 2 evidenced that the bipolar view is no longer valid, and that, crisis proneness rather depends on the macroeconomic fundamentals (the volatility of private sector credit, the deficit-financing mechanism, and the debt-to-GDP ratio). In Chapter 3, we unveiled a strong relationship between ERR and tax policy. Countries with pegged regimes have greater reliance on domestic taxation -such as the VAT- to make up for the loss of seigniorage revenue (substitution effect). Moreover, peggers tend to collect more VAT revenue to offset the shortfall in cross border taxes following the trade liberalization reform (competitiveness effect). Part II discussed the cyclical response of fiscal policy in high debt periods, and focused on fiscal decentralization issues. In Chapter 4, we showed that the reaction of fiscal policy to the business cycle is non-linear and conditional to the level of public debt. When the debt-to-GDP ratio goes beyond a certain threshold (87%), fiscal policy loses its counter-cyclical properties. Further, we highlighted that carefully-designed fiscal rules help maintaining counter-cyclicality through an ex ante disciplinary effect. Chapters 5 and 6 analyzed the impact of fiscal decentralization on the efficiency of public service delivery and fiscal policy performance, respectively. Chapter 5 revealed that a sufficient level of expenditure decentralization, coupled with revenue decentralization, improves the efficiency of public service delivery. However, the political and institutional environment is critical for reaping decentralization-led benefits. Lastly, Chapter 6 concluded that fiscal decentralization has destabilizing effect by reducing the counter-cyclicality of fiscal policy. In addition, we found that decentralization strengthens the structural fiscal balance; however, vertical fiscal imbalances reduce the benefits of decentralization. It is therefore critical to limit asymmetries between expenditure and revenue decentralization, so as to reduce the transfer-dependency of local governments to the central level, and thus prevent decentralization from weakening the fiscal stance at the general government level.

The financial crisis of 2007/8 has triggered a profound debate about public budget finance sustainability, ever-increasing government expenditures and the efficiency of fiscal policy measures. Given this context, the following dissertation provides four contributions that analyze the long-run growth of government spending throughout economic development, discuss potential effects of fiscal policy measures on output, and provide new insights into the assessment of debt sustainability for a variety of industrialized countries. Since the breakout of the European debt crisis in 2009/2010, there has been a revival of interest in the long-term growth of government expenditures. In this context, the relationship between the size of the public sector and economic growth - often referred to as Wagner's law - has been in the focus of numerous studies, especially with regard to public policy and fiscal sustainability. Using historical data from the mid-19th century, the first chapter analyzes the validity of Wagner's law for five industrialized European countries and links the discussion to different stages of economic development. In line with Wagner's hypothesis, our findings show that the relationship between public spending and economic growth has weakened at an advanced stage of development. Furthermore, all countries under review support the notion that Wagner's law may have lost its economic relevance in recent decades. As a consequence of the 2007/8 financial crisis, there has been an increasing theoretical and empirical debate about the impact of fiscal policy measures on output. Accordingly, the Structural Vector Autoregression (SVAR) approach to estimating the fiscal multipliers developed by Blanchard and Perotti (2002) has been applied widely in the literature in recent years. In the second chapter, we point out that the fiscal multipliers derived from this approach include the predicted future path of the policy instruments as well as their dynamic interaction. We analyze a data set from the US and document that these interactions are economically and statistically significant. In a counterfactual simulation, we report fiscal multipliers that abstract from these dynamic responses. Furthermore, we use our estimates to analyze the recent fiscal stimulus of the American Recovery and Reinvestment Act (ARRA). The third chapter contributes to the existing empirical literature on fiscal multipliers by applying a five-variable SVAR approach to a uniform data set for Belgium, France, Germany, and the United Kingdom. Besides studying the effects of expenditure and tax increases on output, we additionally analyze their dynamic effects on inflation and interest rates as well as the dynamic interaction of both policy instruments. By conducting counterfactual simulations, which abstract from the dynamic response of key macroeconomic variables to the initial fiscal shocks, we study the importance of these channels for the transmission of fiscal policy on output. Overall, the results demonstrate that the effects of fiscal shocks are limited and rather different across countries. Further, it is shown that the inflation and interest rate channel are insignificant for the transmission of fiscal policy. In the field of public finances, governmental budgetary policies are among the most controversial and disputed areas of political and scientific controversy. The sustainability of public debt is often analyzed by testing stationarity conditions of government's budget deficits. The fourth chapter shows that this test can be implemented more effectively by means of an asymmetric unit root test. We argue that this approach increases the power of the test and reduces the likelihood of drawing false inferences. We illustrate this in an application to 14 countries of the European Monetary Union as well as in a Monte Carlo simulation. Distinguishing between positive and negative changes in deficits, we find consistency with the intertemporal budget constraint for more countries, i.e. lower persistence of positive changes in some countries, compared to the earlier literature.

思及當前捉襟見肘的財政窘境，無可避免地，債台高築的臺灣實陷入飲鴆止渴般以債養債之無限迴圈中，導致政府政策效能不彰、社會福利運作生弊亦無可厚非；於『公共債務法』之財政規範下，臺灣業已瀕臨法定舉債門檻，故不論是對短期政府支出之排擠、扭曲性稅率之稽徵抑或對長期經濟成長的斲傷，皆是身為中華民國國民真正惶悚不安之所在。 職是之故，本研究係採用一納入政府財政部門及貨幣當局之擴充『實質景氣循環模型』，藉以Sidrauski（1967）所提出的貨幣效用函數為出發點，將實質餘額引進理論模型，並透過計量操作捕捉實證期間起於西元1971年第一季迄至2007年第四季之政府政策函數，過程中，我們不難發現政府購買性支出及稅率皆存在相當的持續性，且對政府未償公債餘額之高低作出某種程度的反應。亦即，若政府實施公債融通政策，俾使期初公債餘額較高之際，則本期甚或往後各期的政府支出將遭受抑制和排擠，尤有甚者，政府勢必擬以提高未來稅率以茲挹注該債務之還本付息所造成的財政缺口；是以，本研究著眼於引進公債餘額對政府支出及稅率存在反饋作用下，財政政策與貨幣政策之總體效果及各總體變數之動態調整過程的風貌。即便公債發行或賒借為政府提供一財務週轉工具以裨益財政政策保有更靈活之彈性，然據模型所產生的結果顯示，就長期而論，政府必須維持一穩定之未償公債餘額，即公債水準具備『均數復歸』性質，而該財政目標係透過削減未來政府支出、調整扭曲性稅率及鑄幣稅融通政策方得以達成預算平衡，準此，該設定將造成公債融通之減稅政策對經濟體系具有實質效果，『公債融通』管道亦『非中立性政策』，從而傳統『李嘉圖等值定理』於本模型中無法成立。 就政策面層次而言，本研究試圖放寬『反饋法則』與政策係數之設定，以檢視透過不同程度之政府支出、稅率甚至貨幣供給途徑的改變來平衡因增加公債發行所造成的財政赤字，對經濟體系之長短期效果有何迥異處；是文亦藉由衝擊反應函數分別探討於政府支出增加、減稅措施及貨幣擴張之下，政策的傳遞機制與各總體變數之動態性質，顯然地，就高債務比率前提下，當政府戮力於刺激景氣而欲積極實施立竿見影的總體經濟政策之際，卻常因狃於急效而欲速不達，非但政策效果有限，亦可能使體系落入更為不景氣的田地，從而，財政惡化不啻為經濟危機的導火線也就不言而喻。再者，貨幣政策對體系之實質變數具有一定程度的作用，是故，本模型於短期內無法一窺『貨幣中立性』之堂奧，唯長期始得以復見。總括言之，政府亟須奉『健全財政』為圭臬，擬定政策時更得戒慎恐懼，並適切權衡利弊得失，以茲裨益有更具信心的經濟表現。 此外，本研究亦透過『效準』實驗以評估模型『配適度』之良窳，即便於反覆疊代法下，該模擬表現係瑕瑜互見而不盡完美，卻也大抵符合景氣循環之『典型化特徵』；然就實質景氣循環模型所為人詬病之勞動市場一隅而論，引進公債之反饋法則下的財政政策操作，無疑地改善了傳統工時與工資率動輒高度正相關之本質，從而獲致相對較低之理論相關係數，亦朝實證資料所呈現工時與工資率存在幾近零相關甚或低度負相關之表徵更邁進一大步。 / With current financial difficulties beyond government capability, it is inevitable that the already deep-in-debt Taiwan opted for momentary relief by paying debt through debt financing and ended up in an infinite loop, causing spiral-down performances in government policies and faulty operations of social welfare instruments. Taiwan has been on the verge of reaching the statutory upper limit of debt financing according to “The Public Debt Act” regulations and all nationals are becoming anxious about such impacts as crowding out of short-run government spending, levying of distorting taxes, and damages on long-run economic growth. To better understand the debt’s impacts, this research uses the “Real Business Cycle Model” extended by taking government treasury agency and monetary institution into account. Starting with Money In Utility Function (MIUF) as proposed by Sidrauski (1967) to introduce real money balance into the theoretical model and, in the process of econometric manipulation, to detect empirical governmental policy functions in the period between the first quarter, 1971 and the fourth quarter, 2007, it is not hard to discover that there are considerable persistence in both government purchases and tax rates, with manifestation of certain degree of responses to the total amount of outstanding bonds the government has yet to pay. In other words, a governmental bond financing policy designed to render high initial bonds outstanding tends to cause suppression and crowding out of government spending in current and even later periods. Furthermore, the government is bound to plan on raising taxes in the future in order to cut financial deficit gap caused by paying back the principles and interests of the debt. Therefore, this study focuses on presenting the macroeconomic effects of fiscal policies and monetary policies, as well as the dynamic adjustment processes of macroeconomic variables based on the impact of feedback effect of bonds outstanding on government spending and tax rates. Even thought public bonds issuance or debt financing serves as a governmental fiscal instrument for financial turnover to ensure flexibility of fiscal policies, our model shows that the government should, from a long-run perspective, maintain a stable amount of bonds outstanding. Put in a different way, the level of bonds outstanding shows “mean-reverting” characteristics which rely on future government spending cut, distorting tax adjustment and seigniorage financing policy to achieve balance of budget. As a result, such setup would cause the bond-financing backed tax deduction policies to create practical effects on economies and, as the bond financing instruments are “Non-Neutrality” policies, would render the “Ricardian Equivalence Theorem” invalid in our model. In the policy aspect, this study tries to relax both “feedback rules” and setup of policy parameters for investigating the differences between long-run and short-run effects on the economy by different degrees of changes in government spending, tax rates and even money supply channels which are used to balance the fiscal deficit caused by increased bond issuance. This article also studies, through the impulse response function, the policy propagation mechanism and the dynamics of key macroeconomic variables under the situation of government spending increase, tax deduction and monetary expansion. It is obvious that the government, in the case of high debt ratios and when making all endeavors to spur economy by implementing macroeconomic policies aimed for instant results, is accustomed to seeking quick fixes only to achieve very limited effects, sometimes even to drive the economy into further recession. It is therefore evident that fiscal degradation could lead to economic disaster. Moreover, as the monetary policies have certain degrees of influence on real variables of the economy, this model will not be able to clearly analyze the “neutrality of money” in such a short period of time. The effect will only reveal in the long run. In summary, the government should keep “sound finance” as the highest guiding principle and be extremely cautious in formulating policies in order to weigh all pros and cons discreetly, thus help to achieve a benefiting economic performance that generates more confidence. Furthermore, this study assesses “goodness of fit” of the model through a “calibration” experiment. Although the simulation results show, under recursive method, intermingled good and poor occasions that are beyond satisfaction, they generally agree with the “typical characteristics” of business cycles. However, in the aspect of long-criticized labor market of the real business cycle model, the fiscal policy operation under feedback rules with introduction of public debts for sure has greatly improved on the conventional intrinsic property of high correlation between labor hours and real wage rates, by delivering a relatively low theoretical correlation coefficient, which is a big step towards the empirical results of almost zero or even weakly negative correlation between labor hours and real wage rates.