FINANCE GUIDE

Construction Industry Scheme (CIS) Guide: For UK Electricians

Everything UK electricians need to know about CIS — how the scheme works, the 20% and 30% deduction rates, registering as a subcontractor, gross payment status, monthly contractor returns, and how to reclaim CIS deductions on your annual self-assessment return.

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11 min readUpdated 2026-05-18Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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Key Takeaways

  • 1The Construction Industry Scheme (CIS) requires contractors to deduct tax from payments to subcontractors and pay it directly to HMRC. It applies to electrical installation work on construction projects.
  • 2Electricians registered with HMRC for CIS receive a 20% deduction on labour payments. Unregistered electricians are deducted at 30%. Registering before starting work is financially essential.
  • 3CIS deductions are not a final tax payment — they are advance payments offset against your annual self-assessment tax bill. If deductions exceed your tax liability, HMRC refunds the difference.
  • 4If you engage your own subcontractors (electricians or labourers) on CIS jobs, you are also a contractor. You must register as a contractor, verify your subcontractors, and submit monthly CIS returns to HMRC by the 19th of each month.
  • 5Gross payment status allows qualifying electricians to receive full payment without any CIS deduction. To qualify, you must have a clean compliance record and annual turnover of at least £30,000 (net of materials).
01 · Finance Guide

What Is the Construction Industry Scheme?

The Construction Industry Scheme (CIS) is an HMRC tax scheme that affects contractors and subcontractors working in the UK construction industry. Under CIS, contractors are required to withhold a proportion of each payment made to subcontractors and pay it directly to HMRC as an advance payment of the subcontractor's tax and National Insurance contributions.

  • Who is a contractor under CIS? — any business that pays subcontractors for construction work. This includes main contractors on large projects, housebuilders, local authorities, and any electrician who pays their own subbies or labourers on CIS projects.
  • Who is a subcontractor under CIS? — any individual or business that is paid by a contractor to carry out construction work. Most self-employed electricians working on new builds, commercial projects, or infrastructure projects are CIS subcontractors.
  • What work is in scope? — electrical installation work on construction projects including new builds, commercial fit-outs, industrial installations, and major renovations. Repair and maintenance work on domestic properties (where the end customer is the householder) is generally outside CIS.
  • Purpose of CIS — CIS was introduced to reduce tax evasion in the construction industry. By requiring contractors to withhold tax at source, HMRC ensures advance payment of tax from workers who might otherwise not file returns.

Disclaimer: This guide provides general information about CIS. The rules are complex, and your specific circumstances — particularly whether you are classified as a contractor, subcontractor, or both — determine your exact obligations. Always consult a qualified accountant for advice tailored to your situation.

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02 · Finance Guide

CIS Deduction Rates: 20% and 30% Explained

There are three possible CIS deduction rates. The rate applied depends on your registration status and whether the contractor can verify you with HMRC before payment.

  • 0% — Gross payment status — the contractor pays the full invoice amount with no deduction. Only available to electricians who have been granted gross payment status by HMRC. See the Gross Payment Status section below.
  • 20% — Standard rate (registered subcontractor) — if you are registered with HMRC for CIS and the contractor can verify your UTR, they deduct 20% from the labour element of your payment. On a £1,000 labour invoice, the contractor pays you £800 and £200 goes to HMRC.
  • 30% — Higher rate (unregistered subcontractor) — if HMRC cannot verify you (because you are not registered or provided incorrect details), the contractor must deduct 30%. On the same £1,000 labour invoice, you would receive only £700. On a busy month of CIS work, this difference in cash flow can be substantial.

Remember: CIS deductions apply only to the labour element of your invoice, not to materials. Always invoice labour and materials as separate line items to ensure the correct deduction is made and to protect your cash flow.

03 · Finance Guide

Registering for CIS as an Electrician

Registering for CIS as a subcontractor is straightforward and free. Here is what you need to do before starting work on your first CIS job.

  • Get your UTR first — you cannot register for CIS without a Unique Taxpayer Reference. If you do not have one, register for self-assessment first. See our UTR number guide for electricians for full instructions.
  • Register online or by phone — log in to your HMRC online account and register for CIS, or call the CIS Helpline on 0300 200 3210. Registration adds you to the CIS subcontractor register.
  • Provide your UTR to contractors — before your first payment, give your UTR and National Insurance number to the contractor. They must verify you with HMRC — this is usually done online and takes minutes. The contractor should give you a verification number as confirmation.
  • Request monthly deduction statements — after each payment, your contractor must provide a CIS deduction statement showing the gross amount paid, the CIS deduction made, and the net amount paid to you. Keep these statements — you need them to complete your self-assessment return.
04 · Finance Guide

Gross Payment Status: Getting Paid Without CIS Deductions

Gross payment status is the most favourable CIS position for an electrician. If granted, contractors pay you the full invoice amount with no deduction. You pay all your tax directly to HMRC via self-assessment.

  • Turnover test — for a sole trader, your annual net turnover from construction work (excluding materials) must be at least £30,000. For partnerships and limited companies the threshold is higher.
  • Compliance test — you must have filed all required tax returns on time, paid all tax and NIC on time, and have no outstanding HMRC debts for the previous 12 months. A single late payment or missed return can prevent you from qualifying.
  • Annual review — HMRC reviews gross payment status annually. If your compliance deteriorates, they can withdraw it. This means you must maintain clean compliance permanently to keep the benefit.
  • Cash flow benefit — gross payment status significantly improves cash flow because you receive your full invoice immediately rather than waiting for HMRC to refund deductions at year end.
05 · Finance Guide

CIS Monthly Returns: Your Obligation as a Contractor

If you engage your own subcontractors on CIS projects — whether electricians, labourers, or other trades — you are acting as a contractor. This brings additional monthly obligations to HMRC.

  • Verify before paying — before making the first payment to any subcontractor, you must verify them with HMRC using their UTR and NI number. HMRC's verification service is online and takes seconds. Verification tells you what deduction rate to apply.
  • Monthly return deadline — 19th of each month — you must submit a CIS monthly return to HMRC by the 19th of the month following the payment month. The return lists all subcontractor payments, verification numbers, deductions made, and materials costs. File online via your HMRC business account.
  • Nil returns — if you had no subcontractor payments in a month, you must still file a nil return by the 19th. Failure to file (even a nil return) attracts automatic penalties starting at £100.
  • Pay the deductions over — the CIS deductions you have made must be paid to HMRC by the 22nd of the month (online) or the 19th (by post). These deductions are not your money to hold — late payment attracts interest.

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06 · Finance Guide

Reclaiming CIS Deductions Suffered

CIS deductions withheld by your contractors are advance payments of your tax. At year end, they are offset against your total tax liability via your self-assessment return. If your deductions exceed your tax bill, HMRC refunds the excess.

  • Declare gross income — on your self-assessment return, declare the gross amount of CIS income (before deductions) as your trading income. Do not declare the net amounts received.
  • Enter total CIS deductions — there is a specific box on the self-employment pages of the self-assessment return for CIS deductions suffered. Enter the total from your monthly deduction statements.
  • File early for faster refunds — if you are due a refund (common for electricians with high expenses or lower income years), file your return as soon as possible after 6 April. HMRC typically processes refunds within 4 to 6 weeks of receiving a complete return.
07 · Finance Guide

CIS Record Keeping Requirements

HMRC requires contractors and subcontractors to keep CIS records for a minimum of three years. For subcontractors, this means keeping all CIS deduction statements received from contractors.

  • Subcontractor records — keep all monthly CIS deduction statements from contractors, your invoices (showing gross amount, materials, and labour split), and bank statements showing net payments received.
  • Contractor records — if you are also a contractor, keep subcontractor verification records, all monthly CIS returns submitted, evidence of payments made, and copies of deduction statements issued.
  • Minimum three years — HMRC can open a compliance check into CIS returns up to three years after filing. Keep all records for at least three years, and longer if there has been any dispute or query with HMRC.
08 · Finance Guide

Managing CIS Invoicing with Elec-Mate

Correct invoicing is central to CIS compliance. Separating labour and materials on every invoice ensures contractors deduct CIS on the right amount and protects your cash flow.

CIS-Ready Invoices on Your Phone

Use Elec-Mate's invoicing tool to create professional invoices with labour and materials as separate line items. This ensures your contractor applies CIS deductions only to labour — protecting your cash flow on every job.

Complete Income Records for Self-Assessment

Every invoice you raise in Elec-Mate is stored with date, amount, and client. At self-assessment time, hand your accountant a complete record of gross income alongside your CIS deduction statements — no spreadsheets needed.

Professional CIS invoicing with Elec-Mate

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