CISflow
Free tool · No signup

Free CIS Deduction Calculator (UK) — Labour, Materials & Net Pay

Work out the CIS deduction on a subcontractor invoice in seconds. Enter labour and materials, pick the rate, and get the deduction, the net payment, and the figures for your CIS300 — calculated the way HMRC requires: on labour only, with materials, VAT and CITB excluded automatically.

Next CIS300 due: 19 July — 19 days leftFiled by the 19th of the month after the payment month. From April 2026 even nil months must be filed — miss it and it's an immediate £100 fine. See all deadlines.

THE INVOICE

The work, ex-VAT — the deduction applies to this only.

Ex-VAT. Exempt from the deduction — includes plant hire.

Optional — for the gross total only. Never deducted.

Subcontractor status

Sets the deduction rate. Verification is HMRC's call, not the subbie's — which rate to use.

THE RESULT

CIS deduction

£480.00

20% of the £2,400 labour only

Net to pay subbie

£2,480.00

Gross less deduction

CIS deduction breakdown
LabourDeduction-eligible£2,400.00
MaterialsEXEMPTExempt from deduction£560.00
Gross totalLabour + materials + VAT£2,960.00
Deduction rateOn labour only20%
CIS deduction20% × labour− £480.00
Net paymentWhat the subbie receives£2,480.00
On your CIS300: report gross £2,960.00 (labour + materials, ex-VAT), materials £560.00, and a deduction of £480.00 for this subcontractor.
Excluded from the deduction: £560.00 materials. The CITB levy is a separate contractor liability — it is not a CIS deduction and is not shown here, so don't double-count it.Figures exclude VAT from the CIS300 gross. Verify the subcontractor's status and rate with HMRC.

SAVE THIS CALCULATION

Get it as a client-ready PDF

A clean one-page record — subcontractor labour/materials split, rate, deduction, net pay and the CIS300 figures — ready to drop into the client's file or email to them. Plus the 7-field CIS invoice checklist.

One email with the PDF + checklist. No spam. How we handle your email.

You just did this by hand. CISflow does it from the invoice.

Forward a subcontractor's PDF — CISflow reads the UTR, verification number, labour/materials split and rate, and hands you a finished, HMRC-ready Xero bill to approve. About 20 seconds, any invoice layout.

STAY ON TOP OF CIS

Never miss the 19th

Get a free monthly reminder before your CIS300 is due, plus the occasional practical CIS tip. One short email a month — no spam, unsubscribe any time.

A free monthly CIS deadline reminder + occasional CIS tips. No spam. How we handle your email.

HOW IT WORKS

How CIS deductions work

Under the Construction Industry Scheme, a contractor deducts a percentage from a subcontractor's payment and pays it to HMRC as an advance on the subcontractor's tax. The deduction applies to the labour portion only — materials, VAT and qualifying plant or CIS-exempt costs are never deducted.

The rate depends on the subcontractor's status with HMRC: 20% if they are registered and verified, 30% if they are unverified or not registered, and 0% if HMRC has granted them gross payment status.

So on an invoice of £2,400 labour plus £560 materials at the 20% rate, the deduction is £480 (20% of labour), the subcontractor is paid £2,480, and £480 goes to HMRC and is reported on your monthly CIS300 return, due by the 19th.

Keep reading: labour vs materials split · the 20/30/0% rates · verifying a subcontractor · CIS300 due dates · CIS invoice software.

This calculator is a guide for UK CIS deductions. Always verify a subcontractor's registration and rate with HMRC. CISflow is a tool, not an accountancy or tax service — you remain responsible for figures submitted to HMRC.

FAQ

CIS deduction questions

Is this CIS calculator free?
Yes — free, instant, no signup. Enter the figures and get the deduction, net pay and CIS300 figures immediately.
Does the CIS deduction apply to materials?
No. The deduction is on the labour portion only. Materials, VAT and the subcontractor's own plant are exempt. Including them over-deducts and harms the subbie's cashflow.
What CIS rate should I use — 20%, 30% or 0%?
20% for verified, registered subcontractors; 30% if HMRC can't verify them; 0% if they hold gross payment status. HMRC verification sets the rate — not what the subcontractor tells you.
Is VAT included in the CIS deduction?
No. VAT is never part of the deduction base, and the CIS300 gross figure is reported excluding VAT.
Does CITB count as a CIS deduction?
No. The CITB levy is a separate contractor liability — it is not a CIS deduction and is not netted in this calculation.
Can I get this calculation as a PDF?
Yes — enter your email and we'll send a client-ready PDF of the calculation plus the 7-field CIS invoice checklist. One email, no spam.