CIS for Electricians: The Construction Industry Scheme Explained

The Construction Industry Scheme (CIS) is an HMRC scheme that requires contractors to deduct tax at source from payments made to subcontractors for construction work. The deducted amount is paid to HMRC and counts as an advance payment towards the subcontractor's Income Tax and National Insurance.

CIS was introduced to tackle tax evasion in the construction industry, where subcontracting chains and cash-in-hand payments historically made it easy for income to go unreported. The scheme ensures that tax is collected at the point of payment rather than relying on the subcontractor to declare it later.

For electricians, CIS applies whenever you work as a subcontractor for a CIS-registered contractor. This includes electrical installations, rewires, consumer unit upgrades, distribution board work, testing and inspection (when part of a construction project), fire alarm systems, data cabling, EV charger installations, and solar PV wiring. If you work directly for a homeowner or end client, CIS does not apply — it only covers the contractor-to-subcontractor relationship.

Many electricians work in both worlds: direct domestic work for homeowners (no CIS) and subcontract work for builders, main contractors, or other electrical firms (CIS applies). Understanding how CIS works is essential for managing your cash flow and filing your Self-Assessment tax return correctly.

There are two types of CIS registration: subcontractor and contractor. Most electricians register as subcontractors, but if you engage other electricians to work for you, you may also need to register as a contractor.

The verification process is straightforward. Before paying a subcontractor for the first time, the contractor contacts HMRC (online or by phone) with the subcontractor's name and UTR. HMRC confirms whether the subcontractor is registered and the applicable deduction rate (0%, 20%, or 30%). This verification must be done before each new subcontractor relationship and refreshed periodically.

The CIS deduction rate depends on your registration status with HMRC. There are three rates — and the gap between them is pure cash flow.

0% = gross payment status; 20% = registered subcontractor; 30% = unregistered.

The deduction applies to the labour element only — materials itemised separately on the invoice are excluded. Gross payment status (0%) is available if you meet HMRC's turnover, compliance and business criteria, covered in the next section.

Put it in real terms. The table below shows the same £60,000 of annual CIS labour income at each rate — every pound deducted is still credited back through Self-Assessment, but the timing of when you see the cash is very different.

The deductions are not lost — they are credited against your tax bill. But the cash flow difference is significant. Register for CIS at minimum, and work towards gross payment status if you qualify.

Gross payment status is the gold standard for CIS subcontractors. No deductions are taken from your payments — you receive 100% and pay your tax through Self-Assessment as normal. To qualify, you must meet three criteria:

Apply for gross payment status through HMRC's online CIS service or by calling the CIS helpline. HMRC will review your compliance history and, if approved, update your status. Contractors who verify you will then see the 0% deduction rate.

Important: HMRC reviews gross payment status annually. If you fail a compliance check (for example, by filing a late tax return), your gross status can be revoked and you will revert to the 20% rate. Maintain your compliance record to keep gross payment status.

If you are registered as a CIS contractor (because you pay subcontractors for construction work), you must file monthly CIS returns with HMRC. These are due by the 19th of every month for the previous tax month (6th to 5th).

You must also provide each subcontractor with a CIS payment and deduction statement within 14 days of the end of each tax month. This statement confirms the gross amount paid, the deduction taken, and the net amount received. The subcontractor needs these statements to complete their Self-Assessment return.

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The VAT Domestic Reverse Charge (DRC) for construction services came into effect on 1 March 2021. It fundamentally changes how VAT works between VAT-registered businesses in the CIS chain — and if you get it wrong, HMRC can issue penalties.

Under the DRC, when you (as a VAT-registered subcontractor) supply CIS-regulated services to a VAT-registered contractor, you do not charge VAT on your invoice. Instead, the contractor accounts for the VAT themselves through the reverse charge mechanism. The invoice must clearly state that the DRC applies.

The DRC has a significant cash flow impact. Previously, you would charge 20% VAT and receive it from the contractor, then pay it to HMRC on your VAT return. Now, under the DRC, you do not receive the VAT at all — meaning your cash receipts are 20% lower. You can still reclaim VAT on your business purchases through your VAT return, which may result in a VAT repayment position rather than a payment.

If you use the Flat Rate Scheme, be aware that DRC supplies are excluded from the flat rate calculation. You account for them under normal VAT rules alongside your flat-rate supplies.

CIS deductions apply to the labour element of your payment — not to materials. If you supply materials as part of a job, the cost of those materials should be excluded from the CIS deduction calculation. However, this only works if you separate labour and materials on your invoice.

Elec-Mate's invoice app separates labour and materials automatically when you create CIS invoices. This ensures the correct deduction is applied and you do not overpay.

When you file your Self-Assessment tax return, CIS deductions are offset against your Income Tax and National Insurance liability. If the deductions exceed your liability, HMRC will issue a refund.

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CIS is not complicated, but electricians regularly make mistakes that cost them money. Here are the most common errors and how to avoid them:

The simplest way to avoid these mistakes is to use proper invoicing software that handles CIS formatting automatically, keep digital records of every payment and deduction, and review your CIS position with your accountant at least quarterly. Elec-Mate's invoice app handles the labour/materials split, CIS formatting, and DRC notation automatically — so you get it right every time.