The Construction Industry Scheme (CIS) is the HMRC system for deducting tax at source from construction sub-contractors — including electricians. This guide covers registration, 20% vs 30% deduction rates, monthly returns, and what happens if you ignore it. This guide is for self-employed electricians doing any sub-contract work.
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CIS (Construction Industry Scheme) is HMRC’s tax-at-source system for construction sub-contractors, introduced 1971 and reformed several times since. The contractor (the main builder, electrical contractor or principal) deducts tax from your invoice before paying you. HMRC then credits the deduction against your annual tax bill. It exists because historically construction sub-contractors had a high rate of self-assessment non-compliance.
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Any electrician who: works as a sub-contractor for another contractor on construction work (defined broadly — includes most electrical install work on building sites), is paid through CIS-recognised contracts, is not on PAYE for that contractor. Domestic small jobs direct to a homeowner are NOT CIS work. Doing the occasional day at a commercial site for another sparky IS CIS work.
Register via the HMRC online service (gov.uk/register-cis-subcontractor). You need: your Unique Taxpayer Reference (UTR), National Insurance number, bank details for refunds. Registration is free. Without CIS registration you are deducted at 30% — registration drops this to 20%. Takes 1-2 weeks for HMRC to process.
After 12 months of CIS compliance + £30,000+ annual turnover, you can apply for Gross Payment Status. Approved sub-contractors are paid in full with no deductions — you settle the tax at year-end through self-assessment. Significant cashflow improvement. Apply via HMRC online service. HMRC reviews compliance annually — late returns or unpaid tax revokes Gross Payment Status.
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If you are a contractor (i.e. hiring sub-contractors), you must file a monthly CIS return to HMRC by the 19th of each month, listing every sub-contractor paid and the deduction made. Late returns: £100 fine + escalating fines. Submit via HMRC online service or via your accountant. Most electrical companies hiring even one sub-contractor have monthly CIS returns alongside PAYE.
Your CIS deductions appear on your self-assessment tax return as tax already paid. If you’ve been deducted £8,000 across the year and your total tax liability is £6,000, you get a £2,000 refund. Many electricians under-claim because they don’t track CIS deductions properly — keep the CIS payment-and-deduction statements from every contractor. Reconcile at year-end.
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A focused action plan based on the guide above.
Get familiar with every section before acting. Skim first, then read carefully — the details matter.
Most readers will have one specific area to act on first (registration, insurance, hiring, pricing). Pick one and focus there.
Inertia is the biggest barrier. Whether it’s phoning your accountant, getting an insurance quote, or applying to a scheme — do one concrete thing this week.
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