How to verify a subcontractor with HMRC
Before you first pay a subcontractor under CIS, HMRC must verify them. Here is when, how, and what to keep.
What verification tells you
When you verify a subcontractor, HMRC tells you whether they are registered for CIS, and what rate of deduction to use or whether you can pay them without deductions. Source: What you must do as a CIS contractor: verify subcontractors.
| What HMRC tells you | Deduction |
|---|---|
| Registered for CIS | 20% |
| Not registered | 30% |
| Gross payment status | 0%, no deduction |
Source: What you must do as a CIS contractor: make deductions and pay subcontractors.
When you must verify
- Before you first pay a new subcontractor.
- Again for a subcontractor you have used before, if you have not included them on a CIS return in the current tax year or the last 2.
Source: What you must do as a CIS contractor: verify subcontractors.
How to verify
Use HMRC's free CIS online service or commercial CIS software. To verify more than 50 subcontractors you need commercial CIS software.
What you need
- Your own Unique Taxpayer Reference (UTR), your HMRC accounts office reference and your HMRC employer reference.
- The subcontractor's UTR.
- For a sole trader, their National Insurance number. Temporary numbers, which start with TN or 2 digits, cannot be verified.
- For a limited company, the company name, company UTR and registration number.
- For a partnership, the nominated partner's details, the trading name and the partnership UTR.
The details must exactly match the ones the subcontractor gave HMRC when they registered. Source: What you must do as a CIS contractor: verify subcontractors.
Keep the verification reference
HMRC gives you a verification reference number. Where HMRC tells you to deduct at the higher rate, you must note the reference and show it on your monthly return and on the subcontractor's payment and deduction statement. Source: Construction Industry Scheme: a guide for contractors and subcontractors (CIS 340).
Our suggestion: keep one record for everyone you pay, with the date you verified them, the reference and the rate. Under the new CIS rules, checks you have written down are how you show HMRC you made reasonable checks. Source: Tackling Construction Industry Scheme fraud (policy paper, 26 November 2025).
What verification does not tell you
Verification shows CIS status and the rate. It does not show whether a limited company is new, behind with its filings or changing directors often. That is on the public register: see how to check a company before you pay a subcontractor.
Questions people ask
Do I need to verify a subcontractor I have used before?
Yes, if you have not included them on a CIS return in the current tax year or the last 2. Otherwise you can pay them at the rate you were given before.
What if HMRC cannot verify a subcontractor?
HMRC will tell you to deduct at the higher rate of 30%, and give you a verification reference with a letter at the end. You must show that reference on your monthly return and on their payment and deduction statement.
Can I verify more than 50 subcontractors at once?
Not in HMRC's free online service. GOV.UK says that to verify more than 50 you need commercial CIS software.
Read on GOV.UK on 26 October 2026. If GOV.UK changes, we change this page.
More guides
- CIS changes April 2026: the new fraud rulesWhat changed on 6 April 2026, and what "knew or should have known" means.
- Gross payment status: the tests, and how you can lose itThe tests, the annual review and the new 5 year cancellation.
- CIS supply chain due diligenceThe test in HMRC's words, the signs it names, and what to record.
- Check a company before paying a subcontractorWhat the Companies House register shows, and what it cannot.
Wherever you build: CIS checks across the UK.