CIS Calculator

Work out the CIS deduction on a construction payment. Enter the labour, materials and plant hire separately and you will get the deduction, the net payment and the full working. No signup, and nothing is sent anywhere.

The invoice

Labour charge The work itself, excluding VAT. This is the only part CIS is deducted from.

Materials Materials the subcontractor paid for. Excluded from the deduction. Use the cost excluding VAT if the subcontractor is VAT registered, otherwise the cost they actually paid.

Plant and equipment hire Hired plant, consumable stores and fuel for plant. Also excluded. Leave at 0 if none.

Subcontractor status

Gross payment status 0% Registered with CIS 20% Not registered with CIS 30%

The standard rate for a subcontractor verified with HMRC.

VAT on this invoice VAT never affects the CIS deduction. Most construction work between VAT-registered businesses now uses the domestic reverse charge.

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I am the contractor I am the subcontractor

The Calculate button is only needed if JavaScript is off. Otherwise results update as you type.

Business Taxation · businesstaxation.co.uk · Tax year 2026/27 · Printed 12 November 2026
Estimate only, not tax advice. Figures should be checked before they are relied on.

You pay the subcontractor

£2,100.00

after a CIS deduction of £400.00 at 20%

How that was worked out

Labour	£2,000.00
Materials no CIS	£500.00
Plant and equipment no CIS	£0.00
Invoice total excluding VAT	£2,500.00
VAT No VAT charged	£0.00
Invoice total	£2,500.00
CIS applies to	£2,000.00
CIS deduction at 20%	− £400.00
You pay	£2,100.00

A single-figure calculator would deduct £500.00

Tax year: 2026/27 (6 April 2026 to 5 April 2027) Rates last checked: 10 September 2026 Source: HMRC: what you must do as a CIS contractor

Your figures, drawn to scale. The green band is the only part CIS is deducted from. Change the numbers above and this redraws with them.

What this CIS tax calculator does #

This CIS deduction calculator works out how much a contractor must hold back from a payment and how much the subcontractor actually receives. The same tool gets searched for under several names, and they all mean the same thing: a CIS tax calculator, a CIS deductions calculator, or a CIS tax deduction calculator.

What separates it from most is that it treats labour, materials and plant hire as three separate figures, because CIS is only ever deducted from labour. Working out a whole tax year instead of one invoice? Use the CIS refund calculator.

Working backwards, and handling VAT #

Two questions come up constantly with this calculator.

Net to gross. If you know what landed in the bank and want the figure before deduction, a CIS calculator net to gross sum is just the reverse. At 20%, the labour element is the net labour divided by 0.8. On £1,600 received against labour, the gross labour was £2,000 and £400 was deducted. Enter the gross figures above and the working is shown either way round.

With VAT. A CIS calculator with VAT has to keep the two apart, because VAT never forms part of the deduction. Set the VAT treatment above and the invoice total changes while the deduction does not. Most construction work between VAT-registered businesses now falls under the domestic reverse charge, where no VAT is charged at all.

The three CIS deduction rates #

Situation	Rate	What it means
Not registered with HMRC	30%	The higher rate. Applied when a subcontractor cannot be verified.
Registered and verified	20%	The standard rate for most subcontractors.
Gross payment status	0%	Paid in full. The subcontractor settles their own tax later.

The contractor must verify every subcontractor with HMRC before the first payment. Verification is what sets the rate. If a subcontractor cannot be matched, the 30% rate applies until they register.

What CIS is not deducted from #

This is where most calculations go wrong. All of the following come out of the payment before the rate is applied:

Materials the subcontractor paid for
Plant hire where the subcontractor incurred the cost
Consumable stores used up on the job
Fuel for plant, though not fuel for travelling
VAT, always, whatever the rate

A calculator that asks for one figure and applies a percentage will overstate the deduction on any job involving materials. On the example above it would deduct £500.00 instead of £400.00. What counts as materials under CIS.

A worked example #

A registered subcontractor invoices £2,000 of labour plus £500 of materials, with no VAT because the domestic reverse charge applies.

Invoice total: £2,500
Materials excluded: £500
CIS applies to the £2,000 of labour
Deduction at 20%: £400
The contractor pays the subcontractor £2,100 and sends £400 to HMRC

That £400 is not lost. It counts as an advance payment of the subcontractor's Income Tax and National Insurance, and it is why so many subcontractors are owed a refund at the end of the year. Work out your CIS refund.

Common questions #

Is CIS deducted from materials?

No. CIS is deducted from the labour element only. The cost of materials, plant hire, consumable stores and fuel for plant are all taken out of the payment before the deduction rate is applied. VAT is also excluded.

What are the CIS deduction rates?

There are three. 30% if the subcontractor is not registered with HMRC, 20% if they are registered and verified, and 0% if they hold gross payment status and are paid in full.

Is CIS calculated before or after VAT?

Before. The deduction is always worked out on the amount excluding VAT. Under the domestic reverse charge no VAT is charged on the invoice at all, but the CIS calculation is unchanged.

How do I stop the 30% deduction?

Register as a subcontractor with HMRC. Once the contractor verifies you, the rate drops from 30% to 20%. On a labour charge of £2,000.00 that is a difference of £200.00 on this invoice alone.