How are home office costs taken into account for tax purposes when used jointly?

When sharing a home office, for example between spouses, the following rules apply:

• The conditions for deducting home office costs are checked individually (BFH rulings of 15.12.2016, VI R 53/12 and VI R 86/13).
• If the conditions are met, each user who uses the home office as their main place of work can deduct the costs they have incurred.
• Property-related costs (e.g., depreciation, interest on loans) are deductible if they are owed by the user (BFH ruling of 6.12.2017, VI R 41/15).
• Rental costs for jointly rented rooms are also deductible, regardless of the type of partnership.
• Usage-related expenses (e.g., energy and cleaning) are fully deductible if they relate to the use of the home office (BMF letter of 15.8.2023, IV C 6 - S 2145/19/10006 :027).

Example 1: A and B use a home office equally. The total expenses amount to 4.000 Euro and are jointly borne by A and B. A uses it as their main place of work. A can deduct 2.000 Euro as business expenses. B can only claim the daily allowance of 6 Euro per day if they worked from home on those days.

Example 2a: A and B jointly use a home office in the apartment rented by B. The expenses amount to 3.000 Euro for rent and 1.000 Euro usage-related expenses. A uses it as their main place of work. A can only deduct 500 Euro (= half of the usage-related expenses). The rental expenses are attributed to B as property-related expenses because B is contractually liable for the rent. B can therefore only claim the daily allowances.

Example 2b: If, on the other hand, A pays the rent, the property-related expenses of 1.500 Euro are also deductible by A.

Example 3: A and B jointly use a home office, which is the main place of business and professional activity for both throughout the calendar year. They waive the calculation of the expenses incurred and can each deduct the annual allowance of 1.260 Euro as business expenses or income-related expenses.