Yes - on the facts you've described, the storage unit rent is an allowable business expense. GOV.UK's guidance on company expenses says a revenue expense is deductible if it isn't specifically disallowed and it has only a business purpose - the 'wholly and exclusively' principle. A unit rented solely to hold your business stock passes that test cleanly, and it's exactly the kind of premises cost that belongs in your company's accounts.
VAT: self-storage services are standard-rated (the standard VAT rate is 20%), so your operator's monthly invoices will carry VAT. If your company is VAT-registered, you can reclaim that VAT on your VAT return as input tax, in the same way as any other business cost. If you're not VAT-registered, the VAT simply forms part of the expense. One check: make sure the invoice shows the operator's VAT number and the VAT amount separately.
Records to keep - HMRC can and does ask for these, so file everything:
- the signed rental agreement (shows the commercial terms and that the unit is for business use);
- every monthly invoice or receipt;
- bank statements showing each payment;
- a brief note confirming the unit holds only business stock - your statement that nothing personal goes in there is the key fact, so write it down and date it.
Keep everything for at least six years from the end of the accounting period, which is the standard record-keeping period.
Two watchpoints. First, duality: the moment you store anything personal in the unit, the 'wholly and exclusively' test fails and the whole deduction is at risk - keep it strictly business. Second, check whether the storage company charges business rates or insurance separately, so you record each cost correctly. Assuming clean business-only use, this is a straightforward deduction.
