If you're a contractor under the Construction Industry Scheme (CIS), you file a CIS300 monthly return with HMRC by the 19th of every month, listing every subcontractor you paid in the previous tax month. AccountantUK builds and submits the return for you.
Before you start
Add the CIS Module to your plan (£10/mo) from Packages. You'll also need to verify your subcontractors with HMRC and log each payment.
Verifying a subcontractor
CIS → Subcontractors → Verify asks for their UTR (plus NINO for sole traders or CRN for companies). We submit a verification request to HMRC; the response comes back in seconds with one of three statuses:
- Gross payment status — no deduction (0%).
- Registered — 20% deduction.
- Unregistered — 30% deduction.
The verification number is stored against the sub and reused on every CIS300 you file with them.
Logging payments
CIS → Payments → New payment:
- Pick the sub.
- Labour payment (subject to CIS deduction).
- Materials (not subject to CIS).
- VAT (separate).
We compute the CIS deduction automatically based on the sub's verified status.
Filing the monthly return
The 6th of each month, the previous month's return appears at CIS → Returns:
- Open the return — every payment in the period is listed.
- Tick the four declarations (employment status considered, unmatched subs verified, information correct, agent or self).
- Submit to HMRC.
- IRmark receipt back in seconds.
Nil returns
If you didn't pay any subs in a month, still file a nil return — HMRC fines for missed months. Open the return, declare nil, submit.
After submission
Each subcontractor automatically gets a Payment and Deduction Statement (PDS) PDF emailed — their evidence of the CIS deducted, used in their own Self Assessment.