Use property commercially?

Good evening everyone,

I'd like to pose the following question to the professionals and experienced among you. I'd like to use part of a property for commercial purposes. Here are the facts.

• The property belongs to my wife (land register), and we live there together.
• The building is a block, but the residential area and the future commercial space are separate.
• The building as a whole has ground floor and top floor
• The future commercial space is in need of renovation (approx. 30,000 euros) plus the roof (approx. 20,000 euros)

Now to my question: I am a business owner and need storage space and a workshop in one.

1. Do I have to rent this space (workshop and warehouse) from my wife in order to claim the investment as business expenses, since the property and building belong to my wife, or is it sufficient if I record these expenses under the accounting account: Assets belonging to operating and business equipment –> Fixed assets?

I renovate everything myself (except for the roof), which means I buy all the materials (cement, wood, electricals, etc.) wholesale for my company.

Thank you very much for your effort.