CIS Deduction UK — Free Calculator 2025

Overview

Calculate CIS Deduction UK using the official rates and regulations for United Kingdom.

How it works

Enter the base amount and the calculator will apply the relevant rates and brackets to compute the result.

What Is the Construction Industry Scheme and Who Does It Affect

The Construction Industry Scheme (CIS) is a set of special tax rules that apply to anyone working in the construction industry in the UK. Under CIS, contractors deduct money from subcontractor payments and pass it directly to HMRC as an advance payment towards the subcontractor's tax and National Insurance liability. The scheme applies to all construction operations including site preparation, demolition, new building construction, alterations, repairs, decorating, and installation of systems such as heating, lighting, and plumbing. Both contractors and subcontractors must register with HMRC for CIS, and failure to register results in higher deduction rates of 30% instead of the standard 20% for registered subcontractors. Companies, partnerships, and self-employed individuals working in construction are all within scope, though employees paid through PAYE are not affected as their tax is already deducted at source by their employer.

CIS Deduction Rates and Registration Status

The deduction rate depends on the subcontractor's registration status with HMRC. Registered subcontractors who have passed HMRC verification face a standard deduction rate of 20% on their gross payments. Subcontractors who cannot be verified or have not registered are subject to the higher rate of 30%, which represents a significant cash flow disadvantage. Subcontractors with a strong compliance history can apply for gross payment status, which eliminates deductions entirely, meaning they receive full payment and settle their tax liability through Self Assessment. Achieving gross payment status requires meeting several tests including tax compliance, business establishment, and construction turnover thresholds of at least £30,000 per year in the three years preceding the application. Many subcontractors view gross payment status as the gold standard, as it eliminates the cash flow delay inherent in the CIS deduction system where overpaid tax is only recovered through annual Self Assessment returns.

Monthly Returns and Compliance Obligations

Contractors must file monthly CIS returns with HMRC by the 19th of each month, reporting all payments made to subcontractors in the previous tax month. The return includes each subcontractor's unique tax reference, verification number, gross amount paid, cost of materials, and the deduction amount. Late filing incurs an immediate £100 penalty, with additional £100 penalties for each subsequent month of delay up to a maximum of £3,000. Penalties for filing incorrect returns follow HMRC's standard regime based on whether errors are careless, deliberate, or deliberate and concealed. Contractors must also verify new subcontractors with HMRC before making their first payment by calling the CIS helpline or using the online verification service. The verification process confirms the subcontractor's identity and tax status, providing a confirmation number that must be included on the monthly return. Material costs are excluded from CIS deductions, as the scheme applies only to labour charges, though distinguishing between materials and labour requires careful record-keeping and can be a source of disputes during HMRC compliance checks.

Reclaiming Overpaid CIS Deductions

Many subcontractors find that the 20% CIS deduction rate results in overpayment of tax throughout the year, particularly those with legitimate business expenses that reduce their actual tax liability. Reclaiming overpaid CIS deductions requires filing a Self Assessment tax return after the end of the tax year, which calculates the total tax liability based on actual income and allowable expenses. The difference between CIS deductions already paid and the final liability is either refunded or offset against other tax debts. Processing times typically range from 2-4 weeks for online filings. Subcontractors expecting significant overpayment can request a repayment during the tax year if they believe deductions will exceed their total liability by at least £1,000, though HMRC applies strict criteria before granting in-year repayments.

Using Our CIS Deduction Calculator

Our CIS deduction calculator helps contractors and subcontractors quickly determine the net payment after CIS deductions, accounting for material costs and registration status. Simply enter the gross contract value, material costs, and your registration status to see the exact deduction amount and net payment you should receive. The calculator supports both the standard 20% rate for verified subcontractors and the 30% higher rate for unregistered workers, providing clarity on the financial impact of CIS registration. For subcontractors considering gross payment status, the calculator can also model the cash flow difference between receiving gross payments versus standard deductions, helping you decide whether applying for gross status is worthwhile for your circumstances.