Deductions in a sole proprietorship: what you can write off
Written by Mads Antonsen · bookkeeper at Numina
Updated July 16, 2026
The basic rule is simple: costs necessary to earn your revenue are deductible. In practice, many owners shortchange themselves — either by missing deductions or by deducting private costs that don't belong in the books.
Typical deductions for the self-employed
- Software and subscriptions (accounting, design and trade software, hosting)
- Phone and internet — reduced for the private share
- Office supplies, equipment and tools (larger purchases are depreciated over several years)
- Business mileage in your own car at the state rate (DKK 3.94/km in 2026)
- Marketing, ads and your website
- Professional training that maintains your existing skills
- Bookkeeper and accountant fees — yes, those are themselves deductible
- Rent for business premises; home office only in special cases
Tax deductions and VAT deductions are two different things
A purchase can give both a tax deduction (the cost reduces your profit) and a VAT deduction (the VAT is reclaimed in the VAT return) — but not always both. A white-plate car, for instance, gives no VAT deduction even where the running costs are tax-deductible. Your bookkeeper keeps the two tracks correctly apart.
Documentation is everything
No receipt, no deduction. Keep the invoice or receipt for every purchase — the Bookkeeping Act requires receipts to be kept for 5 years, and from 2026 most businesses must store them digitally in a registered bookkeeping system.
With Numina you just send the receipt via the app, email or Gmail — we book it, apply the right deduction and store it by the rules.
The classic mistakes
- Private costs in the books — clothes, everyday lunches and an unsplit phone bill
- Lost small receipts — DKK 40 of parking becomes many hundreds over a year
- Training that builds new skills (not deductible) mixed up with maintenance of existing skills (deductible)
- No mileage log — without documentation the mileage deduction is lost
Stop keeping track of all this yourself
Numina's bookkeepers and AI handle bookkeeping, VAT and deadlines for you — at a fixed price with no lock-in. Accounting software included.
Can I deduct my bookkeeper?
Yes. Bookkeeping, accounting and audit fees are operating costs and fully deductible — including your Numina subscription.
How long must I keep my receipts?
5 years after the end of the financial year. From 2026 most businesses must store them digitally in a registered bookkeeping system.
Can I deduct a home office?
Only in limited cases — the room must genuinely be unusable for private purposes. Practice is restrictive, so get a concrete assessment before taking the deduction.