What is the legal basis for the tax-free amount?

The Income Tax Act (EStG), in particular

• § Section 9, 9a of the Income Tax Act (EStG) - Income-related expenses and lump sums
• § Section 10 of the Income Tax Act (EStG) - Special expenses
• § Section 33 of the Income Tax Act (EStG) - Extraordinary expenses
• § Section 35a of the Income Tax Act (EStG) - Tax relief for household-related services and craftsmen's services
• § Section 35c of the Income Tax Act (EStG) - Tax reduction for energy-related measures in buildings used for own residential purposes
• § Section 39 of the Income Tax Act (EStG) - Income tax deduction features
• § Section 39a of the Income Tax Act (EStG) - Allowances