Rent
This concerns the rent of your workspace, studio or workshop. This also includes storage. Depending on the agreements with your landlord, your rent may or may not be taxed with VAT. So check yourself whether your rent is exempt from VAT or whether you can reclaim the 21% VAT.
You usually receive an invoice for this per month or quarter. You can add this to your expenses. Isn't this the case? Then add your rental agreement the first time. This states whether the rent is taxed at 21%. These expenses can be processed monthly without an invoice.
Workspace at your home
Then in a very limited number of cases you are eligible for a deduction of costs. In most cases you may not deduct the costs of the workspace.
The Tax Authorities have a tool to see if your workspace at home is seen as an official workspace. Test it here yourself: https://www.belastingdienst.nl/rekenhulpen/werkruimte/
Workspace interior or renovations
You may only declare the layout of your workspace as costs when you actually rent a workspace of have an official workspace at home. This includes, for example, desks, tables, chairs, plants and the like.