Lancashire has one of the busiest construction sectors in the North West, and Blackburn sits right at the heart of it — from house-building around the outskirts, extensions and refurbs across town, to commercial fit-outs in Blackburn town centre and along the M65. If you’re a subcontractor working under the Construction Industry Scheme (CIS), you’re almost certainly owed a tax rebate every year. The question is how much — and whether you’re claiming everything you’re entitled to.

This 2026 guide is for Blackburn CIS subcontractors — bricklayers, plasterers, joiners, plumbers, electricians, groundworkers, labourers and one-person limited companies working in construction. It covers how CIS actually works, how the tax deduction turns into a Self Assessment rebate, which expenses you can claim, and the common mistakes that leave real money with HMRC.

1. How the Construction Industry Scheme (CIS) actually works

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.

2. Why most Blackburn CIS subcontractors are 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
• Plus Class 2/4 National Insurance
• Refund of roughly £3,000–£4,000 in this scenario

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.

3. Allowable expenses for CIS subcontractors

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.

4. How to claim your CIS rebate — step by step

1. Register as self-employed and for CIS with HMRC if you haven’t already (or as a limited company, which is a separate route with different reclaim rules through PAYE).
2. Gather all monthly CIS deduction statements from every contractor you worked for during the tax year (6 April – 5 April).
3. Add up your income and match it to CIS statements — bank statements are your backup if a contractor didn’t issue one.
4. Total your allowable expenses from receipts, invoices and mileage log.
5. File your Self Assessment (SA100 + self-employment pages) declaring the CIS tax already deducted.
6. HMRC calculates the refund and pays it into your nominated bank account — usually within a few weeks after filing, sometimes with checks.

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.

Common CIS mistakes 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.

Final thoughts

If you’re a Blackburn subcontractor being paid under CIS, there’s a very good chance HMRC is holding onto more of your money than it should be. The combination of accurate record-keeping, every legitimate expense claimed, and a Self Assessment filed on time is usually worth thousands each year — for a fixed accountancy fee that’s a fraction of the refund. Don’t hand a huge chunk of your rebate to a refund-farm firm; work with a local accountant who understands Lancashire construction.

Related reading: Small business accountant in Blackburn: a founder’s guide, VAT returns in Blackburn, and Does Making Tax Digital apply to sole traders?

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, usually within 6–8 weeks of filing.

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. File earlier to get your CIS rebate sooner — HMRC processes rebates in filing order.