What is the CIS 20% deduction?

Under CIS, contractors deduct 20% from payments to registered subcontractors (30% if unregistered) and send it to HMRC as advance tax. If you overpaid, you can claim the difference back.

What expenses can I claim under CIS?

You can claim tools, materials, vehicle costs, fuel, protective clothing, phone, insurance, accountant fees, and other costs directly related to your construction work.

How Does CIS Work? — Plain Language Guide for Construction Workers