Does CIS apply in Scotland and Northern Ireland?

Yes. As of October 2026, the Construction Industry Scheme (CIS) covers construction work anywhere in the UK, including Scotland, Northern Ireland and UK waters to 12 nautical miles, at the same 20% and 30% rates.

CIS is a UK-wide scheme run by HMRC. What changes in Scotland is the Income Tax you owe, which decides how much of your deductions come back. This page follows HMRC's CIS manual, the CIS 340 guide and GOV.UK's Income Tax pages, as checked on 17 October 2026.

Where CIS applies

HMRC's manual on territorial limits says CIS does not apply to construction operations outside the United Kingdom, which it defines as Great Britain and Northern Ireland. That includes UK territorial waters, treated for CIS as reaching 12 nautical miles from the high water mark. It does not include the Irish Republic, the Isle of Man or the Channel Islands.

The manual names wind farms built within territorial waters as caught. Its example of a split contract is a pipeline from an offshore rig to a UK terminal.

The rates are the same everywhere

GOV.UK gives one set of deduction rates: 20% for registered subcontractors, 30% for unregistered ones, and 0% for those with gross payment status. There is no Scottish or Northern Irish rate. The contractor verifies you with HMRC in the same way wherever the site is.

For a sole trader, the deduction counts first towards Income Tax and then towards Class 4 National Insurance, under section 62 of the Finance Act 2004. So the difference in Scotland is not what is taken, but what you owe at the end of the year.

Scottish Income Tax changes your refund

GOV.UK says you pay Scottish Income Tax if you live in Scotland. It also applies if you have no home and spend more days in Scotland than elsewhere in the UK in a tax year, for example staying in hotels or offshore. It depends on where you live, not where the site is. Someone who lives in Glasgow and travels to a site in Manchester pays Scottish rates, and someone who lives in Newcastle and works in Edinburgh does not. Everyone else, Northern Ireland included, uses the main table on GOV.UK's Income Tax rates page, which says only that bands are different if you live in Scotland.

Take an extra £1,000 of labour profit in 2026-27. A contractor deducts £200 at 20%. Here is the Income Tax on that £1,000 at different income levels, with the standard £12,570 Personal Allowance:

Class 4 National Insurance comes on top and is not shown. Between £43,663 and £50,270, the £200 deducted covers less than half of the Scottish Income Tax on that slice, where elsewhere it covers all the Income Tax. A Scottish subcontractor with income in that range can expect a smaller refund, or a bill.

Subcontractors from outside the UK

CIS 340 says the scheme applies to any non-resident subcontractor paid for construction work in the UK, and it does not matter where the payment is made. A non-resident should register before starting work in the UK. Otherwise the contractor must deduct at the 30% higher rate.

The reverse also holds. HMRC's manual says a UK business working on a project overseas should not operate CIS for the subcontractors on that work. A Northern Ireland firm working across the border in the Republic is outside CIS for that job. Ireland's Revenue runs its own withholding tax for construction, Relevant Contracts Tax, with rates of 0%, 20% and 35%.

What this means for you

If you live in Scotland, do not use refund figures worked out for England. The guide to how much tax a CIS subcontractor pays uses rest-of-UK bands, and so does the refund guide. The CIS refund estimator has an "I live in Scotland" box that uses the Scottish bands for 2025-26 and 2026-27. Once your income passes £43,662, set money aside beyond what contractors deduct.

Steps for subcontractors in Scotland or Northern Ireland

1. Register for CIS before you start, so you are deducted at 20% rather than 30%.
2. Keep every payment and deduction statement, wherever the job was.
3. On your online Self Assessment return, tick the box saying you pay Scottish Income Tax if you live in Scotland.
4. Work out your tax using the bands for where you live, not where you work.
5. If you work in the Republic of Ireland, check Revenue's RCT rules for that work.

The free MTD check shows when Making Tax Digital starts for you, and the trades section has more on CIS.