CIS for Subcontractors: The 2026 Guide for UK Tradespeople

If you work in UK construction as a subcontractor, the Construction Industry Scheme (CIS) shapes your monthly cash flow, your year-end tax bill, and your relationship with HMRC. Get it right and the system works in your favour. Get it wrong and you're either lending HMRC money interest-free for 12 months or scrambling to fix verification problems mid-job.

This guide walks through everything that genuinely matters for subcontractors in 2026 — the deduction rates, gross payment status, monthly returns, the Domestic Reverse Charge for VAT, and the MTD ITSA changes coming from April. It's written from the perspective of jobbing subbies and small construction Ltd Cos, not main contractors. Where the rules differ between sole trader and limited company, we flag the difference.

What CIS is and who it catches

The Construction Industry Scheme is a tax-collection regime designed to stop unpaid tax leaking out of the construction sector. It works by making contractors deduct money from subcontractor payments at source — effectively a 20% (or 30%) advance payment of the subcontractor's tax. Subcontractors then reconcile those deductions against their actual tax liability on their Self Assessment or Corporation Tax return.

CIS catches almost every trade involved in building, alteration, repair, decoration or demolition. HMRC's full list is in the CIS 340 guidance, but in practice if you're an electrician, plumber, builder, joiner, decorator, roofer, scaffolder, plasterer, tiler, glazier, demolition contractor or groundworker, you're in scope when you work as a subcontractor.

There are exclusions worth knowing about: professional services (architecture, surveying, structural engineering, planning) are not CIS work; transport and delivery of materials isn't; manufacturing materials off-site isn't; carpet fitting and many security-system installations aren't. Where you're doing a mix, only the construction-operations element falls under CIS.

The three deduction rates: 20%, 30%, 0%

When a contractor pays a subcontractor, the contractor checks the subcontractor's status with HMRC and applies one of three deduction rates:

• 20% — verified subcontractor. This is the standard rate for established subcontractors that HMRC has on its records. It's a deduction from the labour element of the invoice (materials, plant hire, fuel and VAT are excluded from the deductible amount).
• 30% — unverified subcontractor. Applied when the contractor can't verify the subbie's CIS status with HMRC — usually because the subcontractor just started, hasn't given correct UTR/NI details, or has been deregistered. The 30% rate is not a tax in itself; the subbie still reclaims the full deduction at year-end.
• 0% — gross payment status. The subcontractor is paid the full amount with no deduction. Granted by HMRC to subcontractors who meet specific tests (turnover, business presence, compliance history). The cash-flow improvement is significant.

What's deductible matters. CIS deductions only apply to the labour element of the invoice. Materials, plant hire, fuel, manufactured items and VAT are excluded. If you invoice £5,000 in total but £1,500 of that is materials at cost, the deduction is calculated on the £3,500 labour, not the full £5,000.

Gross payment status — the cash-flow game-changer

Gross payment status (GPS) means contractors pay you the full amount with no CIS deduction. You then pay your actual tax bill at year-end through the normal Self Assessment or Corporation Tax process. The cash-flow benefit is real: with the 20% rate, you're effectively pre-paying HMRC roughly 5–6 months of tax ahead of the bill being due. With GPS, that money stays in your business until the bill falls due.

The three tests for gross payment status

HMRC grants GPS only when all three tests are passed:

1. The business test. You must run a genuine UK construction business — not a sham vehicle. HMRC looks for: a business bank account, real records of construction work, normal business contracts, customers and overheads. Sole traders, partnerships and limited companies can all qualify.

2. The turnover test. Your net construction turnover (excluding VAT and excluding the cost of materials) must exceed:

• £30,000 for sole traders
• £30,000 per partner for partnerships
• £100,000 for limited companies (or £30,000 per director if multiple directors)

"Net" here means after deducting materials cost — so a builder who turns over £120,000 of which £50,000 is materials has a net construction turnover of £70,000.

3. The compliance test. This is where most applications fail. HMRC reviews your tax record for the last 12 months and looks for:

• All Self Assessment / Corporation Tax returns filed on time
• All VAT returns filed on time (if registered)
• All CIS300 monthly returns filed on time (if a contractor)
• All PAYE returns filed on time (if employer)
• All tax, NIC, VAT, CIS deductions paid on time

HMRC will tolerate some small lapses — the rules allow a limited number of late returns or payments — but a clean record vastly improves your chances. Subbies commonly miss out on GPS because of a single late Self Assessment from years before. The compliance test repeats annually: once you have GPS, HMRC checks every 12 months that you've stayed compliant. Lose the check, lose the status.

How to apply for gross payment status

The application is straightforward in principle: submit form CIS302 (sole trader) or CIS305 (partnership/Ltd Co), or apply through your HMRC online tax account. In practice, the prep work is more important than the form. We typically spend 2–3 weeks getting a client's compliance position bulletproof before applying — clearing any late filings, settling any outstanding HMRC balance, gathering 12 months of turnover evidence. The application itself takes HMRC about 6 weeks to process.

Monthly CIS300 returns — what contractors must do

If you take on subcontractors, you become a contractor for CIS purposes, even if you're also a subcontractor yourself. You then have monthly obligations:

1. Verify every new subcontractor with HMRC before paying them. Verification confirms the subcontractor's CIS status (20% / 30% / gross). Do this through the HMRC CIS Online service or via accounting software with CIS integration.
2. Apply the right deduction when you pay each subcontractor — based on their verified status and applied only to the labour element.
3. Issue a payment and deduction statement to each subcontractor within 14 days of the end of the tax month in which you paid them. The statement shows gross payment, materials, labour, deduction and net paid.
4. File a CIS300 return monthly by the 19th of the following tax month. This summarises every subcontractor payment made in the previous tax month. Nil returns are still required — if you made no payments at all in the month, you must file a nil return.
5. Pay over the deductions to HMRC by the 22nd of the month (electronic payment) or 19th (postal).

Late CIS300 penalties stack hard. £100 for being one day late. Another £200 after two months. 5% of any unpaid deduction at six months, then again at twelve months. The penalties don't go away even if you eventually file. Subcontractors-turned-contractors can get hit with several thousand pounds of penalties for missing a few months of CIS300 returns — including nil returns they didn't realise they had to file.

Domestic Reverse Charge for VAT (DRC)

This is the rule that catches the most subcontractors out, two years after it landed. Since 1 March 2021, most construction services between VAT-registered businesses operate under the Domestic Reverse Charge. Instead of you charging VAT on your invoice and collecting it, the customer accounts for both the output VAT and the recoverable input VAT on their own VAT return.

When the DRC applies (all five must be true)

1. The supply is a CIS-specified service (most construction work, per CIS 340)
2. Both parties are VAT-registered in the UK
3. Both parties are CIS-registered
4. The customer is not the end user — they're using your work to make an onward supply (e.g. a main contractor with their own customer above them)
5. The supply is standard or reduced-rated (not zero-rated like new-build housing)

If any single one of these fails, you charge VAT normally. The most common reasons it doesn't apply: the customer isn't VAT-registered (most private domestic customers); the customer is the end user (often a landlord doing work on their own property); or the work is zero-rated (new-build residential).

What your invoice must say

Under the DRC, you don't charge VAT but you must show on the invoice that the reverse charge applies and that VAT is the customer's responsibility. HMRC accepts any of these three wordings:

• "Reverse charge: VAT Act 1994 Section 55A applies"
• "Reverse charge: S55A VATA 94 applies"
• "Reverse charge: Customer to pay the VAT to HMRC"

You still show the VAT rate (20% or 5%) and the VAT amount the customer must account for, but you don't add it to the invoice total.

How DRC sales appear on your VAT return

For DRC sales you make (as the subcontractor): include the net value in Box 6 only. No output VAT in Box 1.

For DRC purchases you make (when you're acting as contractor and a sub-subcontractor invoices you): apply both the output VAT in Box 1 and recover it as input VAT in Box 4. The net is in Box 7. The result is tax-neutral but the entry must be made.

The cash-flow effect — plan for it

Before March 2021, a subcontractor would receive £3,000 + £600 VAT and use the £600 as working capital for 60–90 days before paying it to HMRC. That was effectively free credit. Under DRC, you receive only the £3,000. If you've structured your cash flow on the assumption of receiving VAT alongside the labour, the DRC removes a meaningful slice of your working capital. If you're routinely owed VAT refunds (because your input VAT on materials exceeds the small amount of output VAT on B2C work), apply to switch to monthly VAT returns via your HMRC online VAT account to speed up refunds.

End user declarations

Where the customer claims to be the end user (or "intermediary supplier"), the DRC doesn't apply and you charge VAT normally. Get the declaration in writing — an email, letter, or contract clause is enough. Without a written declaration, HMRC's default assumption is that the customer is not an end user. We can provide a one-page template to collect end-user declarations as part of standard job onboarding.

Making Tax Digital for Income Tax — how it hits subbies

From 6 April 2026, sole-trader subcontractors with gross self-employment income over £50,000 must move from one annual Self Assessment to quarterly digital updates plus a final declaration. The threshold drops to £30,000 from April 2027 and £20,000 from April 2028. That April 2028 drop catches almost every full-time sole-trader subcontractor working at the standard 20% deduction rate.

The threshold figure is gross income — turnover before any expenses or CIS deductions are taken off. A subcontractor invoicing £55,000 a year but taking home only £30,000 after expenses is still in scope from April 2026 because the gross figure (£55,000) is above the threshold.

The good news: the underlying tax bill doesn't change. MTD is a reporting change, not a tax-rate change. The practical news: paper records are no longer enough. You need MTD-compatible software, you need to record transactions digitally as you go, and you need to file four short submissions a year plus one final declaration.

For trades specifically, the software choice matters because of CIS. FreeAgent is hard to beat for sole-trader and small-Ltd-Co subbies: automatic CIS deduction calculations, contractor verification, deduction reconciliation against tax bill, MTD ITSA-ready, and free if you bank with NatWest, RBS, Ulster Bank or Mettle. Xero with the CIS add-on works well for larger Ltd Cos. QuickBooks also handles CIS competently.

Limited company subcontractors are not directly affected by MTD ITSA — that regime is for sole traders and landlords with personal Self Assessment liabilities. Limited companies pay Corporation Tax, not Income Tax, and the planned MTD for Corporation Tax was officially scrapped in July 2025.

End-of-year reconciliation: getting your CIS deductions back

For sole-trader subbies, the CIS deductions taken from your payments during the year are credits against your final tax bill on Self Assessment. You enter the total CIS deductions suffered on the SA103 employment pages of your tax return. If the deductions exceed your tax liability, HMRC refunds the excess.

For limited-company subbies, the company recovers CIS deductions against its PAYE and NIC liability, not Corporation Tax. The mechanism is the Employer Payment Summary (EPS) submitted as part of monthly RTI payroll. If CIS deductions exceed PAYE/NIC due, the company can apply to HMRC for a refund at year-end.

This is where we see the biggest single oversight: sole-trader subbies preparing their own Self Assessment forgetting to enter CIS deductions properly, or limited companies not making EPS claims through the year. In either case, the lost money is real — thousands a year for any subbie with steady CIS income.

Common subbie mistakes (and what they cost)

Common patterns we look for when reviewing a subbie's existing tax setup:

• Unverified status sitting at 30% when it should be 20% — usually a UTR mismatch that's never been fixed. Costs cash flow for 12 months until year-end refund
• Gross payment status never applied for despite obvious eligibility. Costs working capital permanently
• Domestic Reverse Charge invoices still showing VAT — either the customer ignores it (cash-flow loss to subbie) or HMRC eventually queries it
• CIS deductions not reconciled on Self Assessment — the deductions sit at HMRC as tax overpaid and never get reclaimed
• Materials invoiced separately to dodge CIS — HMRC sees this. Materials must be genuine materials at cost, not a way to reduce the deduction base
• CIS300 returns missed by subbies who took on a sub-subcontractor for one job, not realising it makes them a contractor
• Capital allowances on the van under-claimed — not a CIS issue specifically, but consistently the biggest single missed deduction in trades returns

If you're switching accountants — what to ask

If you're already with an accountant and the CIS work isn't going smoothly, ask:

• "What's my current CIS verification status, and when was it last checked?"
• "Should I be applying for gross payment status, and if not, why not?"
• "Are all my Domestic Reverse Charge sales coded correctly?"
• "What CIS deductions are sitting at HMRC unreclaimed?"
• "How are we preparing for MTD ITSA?"

If the answers feel vague or incomplete, it's worth a second opinion. Switching accountants mid-year is straightforward — usually 2–3 weeks from confirmation to taking over, with the new accountant handling clearance and record transfer.

How Fernside handles CIS

For sole-trader subbies on the Sole Trader Essentials (£30/mo + VAT) or Sole Trader Plus (£55/mo + VAT) tier: Self Assessment with full CIS reconciliation, MTD ITSA setup and quarterly submissions when applicable, and the gross-payment-status application if you're eligible.

For trades operating through a limited company on the Limited Co Starter (£95/mo + VAT) or Limited Co Growth (£175/mo + VAT) tier: full annual accounts and Corporation Tax, plus CIS300 monthly returns if you take on subcontractors, plus the Domestic Reverse Charge VAT handling on your quarterly VAT returns.

Every set of accounts and every tax return is reviewed by a Chartered Certified Accountant (FCCA) and Chartered Tax Adviser (CTA) before submission — chartered-level oversight on CIS detail that most online accountants at our price point don't offer.

Book a free 20-minute call if you want to talk through your CIS position. Or read our full guide for trades.