CIS Accountant Blackburn: Subcontractor Tax and Rebate Guide

A CIS accountant in Blackburn checks the tax your contractors deduct, claims every allowable expense and files your Self Assessment return so HMRC refunds what you overpaid.

Most subcontractors working under the Construction Industry Scheme are owed money back each year. The question is how much, and whether you are claiming all of it.

Lancashire has one of the busiest construction sectors in the North West, and Blackburn sits at the heart of it, from house-building on the outskirts and extensions across town to commercial fit-outs in the town centre and along the M65.

This 2026 guide is for Blackburn subcontractors: bricklayers, plasterers, joiners, plumbers, electricians, groundworkers, labourers and one-person construction companies. It covers how CIS works, how the deduction becomes a rebate, which expenses you can claim, and the mistakes that leave money with HMRC.

For ongoing help, see our CIS accountant service and how we support construction and engineering businesses across Lancashire.

1. How does the Construction Industry Scheme (CIS) work?

Under CIS, contractors deduct tax from a subcontractor’s pay before handing it over, and pay that tax straight to HMRC. Depending on your CIS status, the deduction rate is:

20% — registered subcontractor with HMRC (standard rate)
30% — not verified / not registered with HMRC
0% — gross payment status (must qualify on turnover, compliance and business tests)

Two really important points that a lot of Blackburn subcontractors miss:

The deduction is only on labour, not materials. If your invoice shows £1,000 labour + £400 materials + VAT, CIS is deducted on the £1,000 only.
CIS is a payment on account of your final tax bill — not the final tax. Whether you owe more or get a refund is only settled when you file your Self Assessment.

Each month the contractor should give you a CIS Payment and Deduction Statement showing gross pay, materials, and tax deducted. Keep every one — they’re your evidence for the rebate.

Why are most Blackburn CIS subcontractors owed a rebate?

The 20% CIS deduction is calculated on your gross labour, before any expenses and before your £12,570 personal allowance. In reality most self-employed subcontractors have significant expenses that HMRC never sees at deduction stage. That gap is your rebate.

A rough real-world example (illustrative — take advice for your own figures):

Gross CIS labour earned in the year: £40,000
CIS tax already deducted at 20%: £8,000
Allowable business expenses: £8,000 (tools, van running costs, mileage, insurance, phone, PPE, accountancy)
Taxable profit: £32,000
Less personal allowance £12,570 → taxed on £19,430
Income Tax at 20% ≈ £3,886
Class 4 National Insurance at 6% ≈ £1,166 (Class 2 is no longer payable)
Refund of roughly £2,950 in this scenario (£8,000 deducted, less about £5,050 actually due)

This example uses the Income Tax rates for England, Wales and Northern Ireland. If you are a Scottish taxpayer, your Income Tax is worked out at Scottish rates, so the figures will differ slightly.

The CIS deduction and Class 4 National Insurance work the same way.

The more expenses and mileage you can properly evidence, the bigger the legitimate refund. This is why keeping receipts and a mileage log matters — every missing receipt is money left with HMRC.

What expenses can CIS subcontractors claim?

If it’s wholly and exclusively for your construction work, it’s usually allowable. Typical claims include:

Tools and small equipment — drills, saws, hand tools, replacements
PPE and workwear — boots, hi-vis, hard hats, branded workwear
Van and vehicle costs — either actual running costs or the flat 45p/mile rate (for the first 10,000 business miles, then 25p) — pick the more beneficial and stick to it
Fuel, parking, tolls and congestion charge (if using actual costs)
Public liability and tool insurance
Mobile phone (business use %)
Materials and consumables you buy for jobs
Subcontractor labour you pay to others (with your own CIS returns)
CITB levies, CSCS card, trade memberships and training courses that maintain skills
Accountancy fees for preparing your accounts and tax return
Use of home as office for quoting/admin (flat rate or actual)
Bank charges on a dedicated business account

What you can’t claim: ordinary clothing (jeans, a normal t-shirt), lunch on the go (unless overnight/away), fines and penalties, or the private-use element of a vehicle. Our guide to allowable expenses sole traders often miss covers the everyday costs that apply to any self-employed trade.

How is the CIS rebate paid?

For a sole trader, the rebate comes through your Self Assessment return. You declare your gross CIS income, your expenses and the CIS tax already deducted, and HMRC repays the difference.

Keep every monthly CIS statement, because HMRC checks your deductions against your contractors’ returns. Our step-by-step guide to claiming a CIS tax rebate covers the claim itself, how long HMRC takes and how to claim for earlier years.

Deadlines: 31 October (paper return) or 31 January (online) for the previous tax year. You can file as early as 6 April — earlier filing usually means a faster rebate.

Limited company subcontractors: CIS deductions are reclaimed monthly against your PAYE liabilities through the EPS, not through Self Assessment. This is a different process and often done incorrectly — a specialist CIS accountant matters here.

What CIS mistakes do we see in Blackburn?

Losing monthly CIS statements — no statement, harder to prove the deduction.
Not claiming mileage properly (this is often the biggest single expense).
Missing the 31 January filing deadline and getting a £100 automatic penalty.
Assuming a “£3,000 rebate” is guaranteed — everyone’s numbers are different.
Working through some contractors as CIS and others cash-in-hand and not declaring the second.
Getting the CIS reverse charge for VAT wrong (this hits VAT-registered subcontractors).
Using cheap online refund firms that take 20–35% of your rebate as a fee.

Frequently Asked Questions

What is CIS and who does it apply to?

The Construction Industry Scheme (CIS) requires contractors to deduct 20% (registered) or 30% (unregistered) from payments to subcontractors and send it to HMRC as an advance on their tax and National Insurance. It applies to most construction operations in the UK.

How do I claim a CIS tax rebate?

Sole trader subcontractors file a Self Assessment tax return each year showing gross income and expenses. HMRC offsets the CIS deducted at source against the actual tax due and refunds any overpayment. A straightforward online claim is often paid within a few weeks, but CIS deductions are checked against contractors’ returns, which can take longer.

What expenses can CIS subcontractors claim?

Common allowable expenses include tools and equipment, protective clothing, vehicle running costs and mileage, public liability insurance, work-related phone use, training that maintains existing skills, and a use-of-home allowance for admin.

When is the CIS Self Assessment deadline?

The online Self Assessment deadline is 31 January following the tax year. You can file from 6 April, and filing earlier gets your CIS rebate into HMRC’s system sooner. HMRC does not publish a fixed refund timescale; the “Where’s my reply” tool in your HMRC online account shows the expected date.

The bottom line

If you are a Blackburn subcontractor paid under CIS, HMRC is very likely holding more of your money than it should.

Accurate records, every legitimate expense claimed and a Self Assessment return filed on time are usually worth far more than the accountancy fee. Don’t hand a big slice of your rebate to a refund firm. Work with an accountant in Blackburn who understands Lancashire construction.

Tax figures checked by Rehan Razzaq FCCA on 8 October 2026 for the 2026/27 tax year.

This article is general guidance for UK businesses and individuals and does not constitute personal financial or tax advice. Rules, thresholds and individual circumstances vary — always confirm your specific position with a qualified accountant before acting.

WRITTEN BY

Rehan Razzaq, FCCA

Founder, R&R Chartered Certified Accountants

ACCA Chartered Certified and Xero Certified Advisor, helping Blackburn businesses and landlords with accounts, tax and financial planning since 2021.

More about Rehan →

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