Millward, May & Co - Wokingham Accountants
Wokingham Accountants

Construction Industry Scheme

CIS Contractor


You will need to register as a CIS contractor if you plan on paying subcontractors for ‘construction work’. CIS covers most construction work to a permanent or temporary building or structure. For the purpose of CIS, construction work includes:

  • preparing the site, e.g. laying foundations and providing access works

  • demolition and dismantling

  • building work

  • alterations, repairs and decorating

  • installing systems for heating, lighting, power, water & ventilation

  • cleaning the inside of buildings after construction work

Click here for instructions on how to register.


As a CIS contractor you have a duty to deduct the correct amount of tax from payments made to CIS subcontractors. In order to know which rate to deduct from your subcontractors (30%, 20% or 0%) you need to verify them with HMRC before you pay them. It’s important that you verify contractors because if you deduct too little from them, you could be liable for the difference!

If we (Millward, May & Co) verify your CIS contractors for you, you’ll need to get them to fill out the following form so that we can verify them:

If you are verifying your CIS contractors, click here to find out how.


You’ll be required to submit a monthly form (called a CIS Return) to HMRC. The CIS Return covers a period from the 6th of every month until the 5th of the next month. The CIS Return along with payment is due 14 days after the period end date on the 19th of the month.

For Example

A CIS period that runs from the 6 January 2000 to 5 February 2000 is due to be submitted and paid by 19 February 2000.

Labour & Materials

The subcontractor will need to split out labour and material costs when they invoice you.

CIS tax is only deducted from labour (not materials) and so some subcontractors may try to inflate the materials split in order to have less tax deducted from their invoice.

It falls on your shoulders to sense check the split between labour and materials because if the wrong tax is deducted you may be liable for the underpayment in tax. You therefore have every right as a contractor to ask for receipts of materials.

Subcontractor Invoices

Invoice Example

If a subcontractor sent you an invoice of £8,000 Labour, £2,000 Materials & £2,000 VAT you wouldn’t pay them £12,000. Instead you’d ‘verify’ them to find out how much tax you need to deduct from them - lets assume that in our example the subcontractor has been verified and that their deduction rate is 20%

  • £8,000 Labour

  • £2,000 Materials

  • £2,000 VAT

  • £12,000 Total (or gross)

  • (£1,600) CIS deduction @ 20% of £8,000 labour cost

  • £10,400 Payment

The total (or gross) amount on a subcontractors invoice is £12,000. Instead of paying them £12,000, you would pay them £10,400 and then pay £1,600 to HMRC on their behalf as part of your CIS Return.

CIS Returns

The information included on your CIS Returns is as follows:

  • The subcontractors Personal/Business Name

  • How much you paid them in Total Payments (Labour & Materials excluding VAT)

  • How much you paid them in Total Materials (excluding VAT)

  • How much CIS Tax you deducted from them

Penalties for late returns

Fines can accumulate quite quickly in the CIS scheme so make sure you’re on top of things. I’ve seen on multiple occasions situations where people have had thousands of pounds in fines!

You’ll get a penalty if you miss the deadline for filing returns. Below is a list of how much you’ll be fined if CIS Returns are submitted late - this is per monthly return!

1 day late = £100

2 months late = £200

6 months late = £300 or 5% of the CIS deductions on the return, whichever is higher

12 months late = £300 or 5% of the CIS deductions on the return, whichever is higher