I am currently working as a freelancer in Belgium for a company developing computer software. In the contract it says that the work is done at client's office and each day I work from the office. I've rented an apartment and the landlord allows me to register it as a business address. My accountant said I can deduct the taxes for 25% of the rent for the apartment if I move the computer office in the bedroom.

In case of a fiscal control(not sure of the name in EU, in US is IRS), is it ok to say that I regularly connect remotely to work from home although in the work contract it says I must work at client's office? Are there any other ways I can prove that this deduction is valid?

Thank you!