To deduct, or not to deduct.

Office space used for meeting clients, selling products, providing services, or conducting work is tax-deductible.

A home office is only deductible if it is a dedicated room (not used for other personal activities) and has a door. A table in the corner of the living room won’t suffice.

Theoretically, business travel is fully deductible. However, the Finanzamt requires detailed proof for the necessity of travel and validity of expenses. Food expenses are deducted separately, not via receipts, but on a per diem basis.

Software required to do the work or deliver the outcome to a customer.

Finanzamt dislikes these expenses because they are difficult to prove as business-related. One option is to have photo proof of the event or catering in addition to the receipts. Obviously, deductible for cafes and restaurants.