You already paid 20% tax through CIS. Every legitimate expense you claim lowers your taxable profit — and most of it comes straight back in your refund after 5 April. Here's what counts.
Say you earned £40,000 through CIS: £8,000 was already deducted. If you claim £5,000 of legitimate expenses, tax is recalculated on £35,000 — the difference lands in your refund. Workers who keep no receipts routinely leave £1,000+ with HMRC every year.
Drills, grinders, hand tools, ladders — bought for work. Big items may be claimed via capital allowances.
Anything you purchase for jobs and aren't reimbursed for.
Boots, hi-vis, helmets, gloves, branded workwear. Not everyday clothes — jeans don't count even if you wear them on site.
Either actual van costs or simplified mileage: 45p/mile for the first 10,000 miles, 25p after. Travel to temporary sites counts.
Public liability and tool insurance are fully claimable.
The business share of your bills — the calls and data you use for work.
CSCS/CPCS/IPAF renewals and courses that update existing skills. Training for a brand-new trade generally doesn't count.
Fees for doing your tax return are themselves deductible.
On work journeys. Parking fines never count.
Union subs and professional memberships related to your trade.
Everyday clothes, ordinary commuting to a single permanent workplace, fines and penalties, most everyday meals, and anything your contractor reimbursed. Claiming these is what triggers HMRC checks — stick to the real list and your refund is safe.
A receipt in your pocket is gone in a week. A receipt photographed the same day, with amount and date, is money in April. Graftum Pocket has an expenses tab built for exactly this — snap the receipt, type the amount, and your tax-year total lands automatically on the CIS statement you hand your accountant. Free forever.
Open Graftum Pocket — freeThe simplified rate is 45p per mile for the first 10,000 business miles in the tax year, then 25p per mile. If you use it, you can't also claim fuel and van running costs — it replaces them.
You can claim expenses you can reasonably evidence — bank and card statements help. Going forward, photograph every receipt the day you get it; that record is what makes your claim solid.
You can usually correct returns and claim overpaid tax up to 4 years back. An accountant can bundle past years into one claim — bring them whatever records you have.
General information, checked September 2026 against gov.uk guidance — not tax advice. Your accountant applies this to your case.