CIS Contractors: Monthly Tax Chores and HMRC Obligations – Updated for April 2026

The Construction Industry Scheme (CIS) is a set of HMRC rules governing how tax and National Insurance are handled between contractors and subcontractors in the UK construction industry. Understanding your CIS contractor responsibilities is essential if you pay subcontractors for construction work, as you have ongoing monthly obligations that must be met to avoid financial penalties.

CIS contractor responsibilities do not end when the business registers for the scheme. Contractors must continue to verify subcontractors, calculate CIS deductions correctly, maintain records, submit CIS monthly returns and make CIS payments due to HMRC.

For a full overview of how the Construction Industry Scheme works, including who it applies to and how deductions are managed, our dedicated guide to the Construction Industry Scheme covers the complete framework.

From 6 April 2026, HMRC has introduced the most significant changes to CIS in a decade, announced in the Autumn Budget 2025. Monthly nil returns are now mandatory again, a full penalty regime has been reinstated, new anti-fraud measures have been introduced, and public sector exemptions have been updated. Every contractor must understand what these changes mean in practice.

This guide, prepared by the specialist construction accountants at CIGMA Accounting, covers CIS contractor duties, the new 2026 rules, the penalty structure you now face, and how to stay compliant with HMRC.

What Is the Construction Industry Scheme (CIS)?

The Construction Industry Scheme is a mandatory HMRC framework that applies to contractors and subcontractors working in the UK construction sector. Under CIS:

• Contractors must register with HMRC before paying subcontractors
• Contractors must verify subcontractors with HMRC before making the first payment
• Contractors must deduct either 20% or 30% from payments to unregistered or higher-risk subcontractors (nil deduction for those with gross payment status)
• Those deductions are passed directly to HMRC as advance payments toward the subcontractor’s Income Tax and National Insurance
• Contractors must file a monthly return with HMRC recording all payments and deductions made

Subcontractors receive a monthly deduction statement showing how much has been deducted, which they use to offset against their annual tax bill.

These requirements form the core CIS contractor duties. Contractors need processes that connect subcontractor verification, CIS payments, CIS deductions and monthly reporting so that the same transaction is treated consistently throughout the compliance cycle.

Who Has CIS Contractor Responsibilities?

You are classified as a contractor under CIS if either of the following apply:

• You pay subcontractors to carry out construction work on your behalf
• You have spent more than £3 million on construction in the 12 months since making your first payment – even if your primary business is not construction

This second point catches many businesses by surprise. Property developers, housing associations, and large non-construction businesses that commission significant building work can all fall within the CIS contractor definition.

Once a business falls within that definition, its CIS contractor responsibilities apply to qualifying subcontractor arrangements regardless of whether construction is the organisation’s main trade.

For high-revenue construction businesses navigating CIS for the first time or managing significant subcontractor volumes, our guide on CIS compliance for high-revenue construction companies covers the specific obligations and risks that apply at this scale.

What Construction Work Falls Under CIS?

CIS applies to a wide range of construction operations, including:

• Site preparation, groundwork, and excavation
• Building, altering, repairing, or demolishing structures
• Installing systems such as heating, plumbing, lighting, and ventilation
• Cleaning the inside of buildings after construction or renovation
• Decorating and finishing work

It does not apply to professional services such as architecture, surveying, or building inspection, nor to the manufacture and delivery of materials (where no installation is involved).

CIS Contractor Responsibilities – What Every Contractor Must Do Monthly

The main CIS contractor responsibilities repeat throughout the year. Contractors need to verify new subcontractors, apply the correct deduction treatment, report relevant payments and deductions, issue statements and make the required CIS payments to HMRC.

1. Verify Subcontractors Before First Payment

Before paying a subcontractor for the first time, you must verify them with HMRC using the CIS online service or approved commercial CIS software. HMRC will confirm one of three statuses:

• Gross payment status – no deduction is made
• Net payment (20% deduction) – the standard deduction for registered subcontractors
• Higher rate (30% deduction) – applies to unverified or unregistered subcontractors

Verification must be repeated if you have not used that subcontractor within the current or previous two tax years.

Verification is one of the most important CIS contractor duties because the result determines how the contractor treats subsequent payments. Using an incorrect status can lead directly to incorrect CIS deductions.

2. Make the Correct CIS Deductions

Once verified, deduct the correct percentage from the labour element of each payment. Do not deduct from materials, VAT, or equipment hire costs – these are excluded from CIS deductions.

Keep a record of every payment and deduction. You must provide each subcontractor with a monthly payment and deduction statement showing what was paid and deducted.

Accurate CIS deductions depend on both the verified subcontractor rate and the amount of the payment that is subject to CIS. Contractors should therefore retain sufficient detail to explain how each deduction was calculated.

3. CIS Contractor Responsibilities for Monthly Returns

Every contractor must submit CIS monthly returns to HMRC covering each tax month – which runs from the 6th of one month to the 5th of the next.

The return must include:

• Details of every subcontractor paid during the month
• The gross amount paid to each subcontractor
• The amount of any deductions made
• Confirmation that employment status checks have been carried out

CIS monthly returns bring together the payment and deduction information accumulated during the tax month. Reconciling the return against subcontractor records before filing can help identify missing payments, duplicated entries or incorrect deductions.

For a detailed breakdown of exactly what your monthly CIS return must include and how to submit it correctly, our guide on CIS monthly return obligations covers the full process.

4. Make CIS Payments to HMRC

CIS deductions collected from subcontractor payments must be paid to HMRC. For most contractors this is due by the 19th of the month following the tax month (22nd if paying electronically). These CIS payments are made alongside your PAYE liabilities.

Keeping CIS payments separate from the contractor’s normal operating cash is useful for cash-flow management because amounts deducted from subcontractors are being held for payment to HMRC rather than representing income belonging to the contractor.

NEW FROM 6 APRIL 2026 – CIS Contractor Responsibilities and Key Changes

Mandatory Monthly Nil Returns Are Back

The biggest change announced in the Autumn Budget 2025 is the return of compulsory monthly CIS nil returns. From 6 April 2026, if you have not paid any subcontractors in a given tax month, you must either:

• Submit a CIS nil return by the deadline, or
• Notify HMRC in advance by submitting an inactivity request for that period

This requirement was originally removed in 2015 to reduce administrative burdens. However, many contractors failed to keep HMRC updated, which led to mounting penalties and a high volume of appeals – prompting HMRC to reinstate the obligation.

An inactivity request can cover up to 6 months at a time. If you start using subcontractors again during an inactivity period, you must notify HMRC immediately.

This means managing CIS monthly returns remains one of the recurring CIS contractor responsibilities even during periods when no subcontractor payments have been made.

The Full CIS Late Filing Penalty Regime Is Reinstated

With nil filing now mandatory again, HMRC has reinstated the full CIS late filing penalty structure. A £100 fixed penalty applies for any late return. Further charges escalate as follows:

• After 2 months late: additional £200 fixed penalty
• At 6 months late: minimum £300 or 5% of the CIS liability shown on the return – whichever is higher
• At 12 months late: further tax-geared penalty applies

There is no grace period – even filing one day late triggers an automatic penalty. If you believe a penalty was issued incorrectly, you normally have 30 days to appeal either online or in writing.

New Deadline – CIS Monthly Returns Due by the 19th

From April 2026, CIS monthly returns must be submitted to HMRC by the 19th of every month, following the end of the last tax month. This is a change from the previous 14-day rule – note that the deadline is now the 19th, not the 14th.

Updating your filing processes to reflect this change is essential – our guide on best practices for filing accurate and timely CIS returns sets out the practical steps contractors should follow to stay compliant under the new rules.

Public Sector Exemptions – Simpler Rules for Local Authority Work

From 6 April 2026, payments made to local authorities and certain public sector bodies are completely exempt from CIS under new Regulation 24ZA. This removes the need for deductions and reporting on qualifying public-sector contracts – replacing a previous concession that required public bodies to be treated as having gross payment status.

Importantly, development subsidiaries paying their parent housing association for construction work will no longer need to apply CIS to these payments.

New Anti-Fraud Powers for HMRC

New measures have been introduced to tackle fraud in construction supply chains. HMRC now has greater powers where a business knew or should have known that payments were connected to fraud – including the ability to remove gross payment status immediately and charge penalties of up to 30% in fraud-connected situations.

HMRC can charge the business that made the payment 20% of the amount paid, and charge the business that claimed the CIS deduction 10% of the deduction claimed.

Contractors should review all supply chain labour arrangements and document due diligence procedures, particularly where agency workers, umbrella companies, or multi-tier subcontracting is involved.

These anti-fraud measures add another layer to CIS contractor responsibilities. Contractors need to consider not only whether routine CIS deductions and CIS monthly returns are correct, but also whether appropriate checks have been performed on more complex supply-chain arrangements.

For high-revenue construction businesses managing complex supply chains, our guide on essential CIS compliance strategies for larger construction companies sets out the additional steps needed to manage fraud risk and maintain HMRC compliance at scale.

CIS Monthly Return Deadlines – Summary Table

CIS Penalty Summary – What You Face for Late Filing

Common CIS Contractor Duties and Monthly Mistakes to Avoid

Many penalties arise not from intentional non-compliance but from easily avoidable errors. The most common issues CIGMA Accounting sees include:

• Forgetting nil returns – the most frequent mistake since 2026, now that nil returns are compulsory again
• Deducting from materials – CIS deductions only apply to labour, not materials, VAT, or equipment hire
• Failing to re-verify – subcontractors not used in two consecutive tax years must be re-verified
• Using the wrong deduction rate – paying the 20% rate without proper verification when 30% should apply
• Missing the 19th deadline – the deadline changed in April 2026 and some contractors are still using the old 14-day calculation
• Not issuing deduction statements – subcontractors are legally entitled to a monthly statement

These errors show why CIS contractor duties should be managed as a repeatable monthly process. A checklist covering verification, CIS deductions, statements, CIS monthly returns and CIS payments to HMRC can reduce reliance on memory and help maintain consistent records.

Our guide on common mistakes that lead to CIS penalties explains each of these errors in detail and sets out exactly how to avoid them.

How CIS Deductions Interact with VAT Reverse Charge

If you are VAT-registered and work in construction, the domestic reverse charge for construction services also applies. Under this rule, the customer (rather than the supplier) accounts for VAT on CIS-covered services.

This means CIS deductions and VAT reverse charge can apply simultaneously on the same invoice – creating a dual compliance obligation that catches many contractors out. Your CIS monthly returns and VAT returns must both reflect these transactions correctly.

If you are managing both obligations, professional software or specialist accountant support is strongly recommended.

How CIGMA Accounting Supports CIS Contractor Responsibilities

At CIGMA Accounting, our specialist team supports contractors across London and the UK with every element of their CIS compliance:

• CIS monthly returns preparation and submission
• Subcontractor verification with HMRC
• Correct CIS deductions calculation
• Monthly payment and deduction statements for subcontractors
• CIS penalty appeal support
• CIS and VAT reverse charge reconciliation
• Gross payment status applications
• Supply chain due diligence reviews following the 2026 anti-fraud changes

For contractors managing several subcontractors, outsourcing recurring CIS contractor responsibilities can help ensure that verification, CIS payments, deduction statements and CIS monthly returns remain consistent with the underlying accounting records.

Case Study: Correcting CIS Deductions Before the Monthly Return

A construction contractor approached our Fulham Broadway office after noticing that payments to several subcontractors did not consistently match the amounts shown on its CIS records. The business was using both the 20% and 30% CIS deduction rates, but its accounts team was unclear about which parts of each subcontractor invoice should actually be included in the deduction calculation.

Cigma Accounting reviewed the subcontractor verification results, invoices and payment records. We confirmed that the deduction rate should follow the status returned by HMRC rather than being selected simply from information provided by the subcontractor. Registered subcontractors were generally subject to the standard 20% CIS deduction, while the higher 30% rate applied where HMRC verification required it.

The review also identified that some deductions had been calculated by applying the relevant percentage to the entire invoice. We helped the contractor establish the amount properly subject to CIS before applying the verified rate, rather than treating every invoice component as automatically deductible.

We then reconciled the corrected calculations with the contractor’s payment and deduction statements and monthly CIS records. This allowed discrepancies to be identified before incorrect figures were carried into the CIS300 monthly return and reduced the risk of repeated errors across future subcontractor payments.

As part of the wider engagement, Cigma Accounting supported the company with CIS returns, construction bookkeeping, payroll and VAT accounting. We also introduced a clearer process for recording HMRC verification results and reviewing subcontractor deductions before payments were authorised.

The contractor was left with a more reliable CIS calculation process and greater confidence that its CIS deductions, payment records and monthly HMRC return could all be reconciled.