The Swedish Tax Office, Skatteverket, aims at providing a good service to its customers in order to favor compliance to taxes. The Tax Audit process of businesses plays a key role in this as Skatteverket and the taxpayer interact directly within this process. The focus of this thesis is to apply Lean philosophy to improve the Tax Audit process. Eliminating non value-adding steps, developing visual management tools and implementing a continuous improvement mindset are the tools used to achieve it. This Thesis states the observations of the current situation and develops three projects led by Lean. First one is a customer portal, an online platform which gathers all relevant information about the Audit. Second is the time reduction of an administrative process and last one consists in the improvement of the Pulsemeeting.