How Do I Claim for Materials Supplied on a CIS Job

If you work in the construction industry as a subcontractor, you may already be familiar with the Construction Industry Scheme (CIS). Under CIS, contractors deduct tax from your payments before you receive them. However, if you supply materials or certain costs as part of your work, these should not be included in the taxable amount. Understanding how to claim for materials correctly ensures you are paid fairly and not overtaxed. This article explains what counts as materials under CIS, how to claim for them, and what records you need to keep for HMRC.

What counts as materials under CIS

HMRC defines materials as anything that is used or incorporated into the construction work you carry out. This includes both items you buy directly for the job and the cost of materials you already own that are used up in the process.

Examples of materials that can be claimed include:

  • Building supplies such as bricks, timber, concrete, or plasterboard.

  • Fixtures and fittings that become part of the completed work.

  • Fuel used to power machinery or transport materials (if specifically for the job).

  • Hire of plant or machinery needed to complete the project.

  • Consumables such as nails, sandpaper, and protective coverings.

Materials do not include your labour costs, tools that remain your property, or general overheads like phone bills, insurance, or office expenses.

How contractors should treat materials under CIS

When paying a subcontractor, a contractor must calculate CIS tax only on the labour portion of the payment. The cost of materials should be excluded before applying the 20% or 30% deduction.

For example:

If your invoice to a contractor is £5,000, made up of:

  • £3,000 for labour

  • £2,000 for materials

The CIS deduction should apply only to the labour amount.

  • CIS at 20% of £3,000 = £600

  • Total payment due = £5,000 – £600 = £4,400

If the contractor incorrectly deducts CIS on the full £5,000, you would be overpaying tax and may need to recover the difference through your Self Assessment tax return.

How to claim for materials on your invoice

When invoicing for CIS work, it is important to clearly separate labour and material costs. This helps the contractor calculate the correct CIS deduction.

Your invoice should include:

  • A detailed description of the work carried out.

  • The total cost of labour.

  • The total cost of materials and any hire or fuel costs.

  • The total before and after the CIS deduction.

Example invoice layout

Description Amount (£)

Labour (3 days @ £250) 750

Materials (cement, timber, paint) 300

Subtotal 1,050

CIS deduction (20% on labour £750) 150

Amount payable 900

This breakdown shows the contractor exactly how to apply CIS, preventing misunderstandings and ensuring you are not over-deducted.

Providing evidence of materials

Contractors are required to make sure the materials claimed are genuine business costs. To support your claim, keep clear records of all materials purchased for each job.

Evidence should include:

  • Supplier invoices and receipts showing the materials bought.

  • Delivery notes or purchase orders referencing the project.

  • Hire invoices for plant or equipment.

  • Proof of payment, such as bank statements or card receipts.

If HMRC ever reviews your CIS records, this documentation will prove that your materials were legitimate business expenses.

What if the contractor deducts CIS on materials by mistake

If your contractor has deducted CIS on the full amount, including materials, you can recover the overpaid tax when you file your Self Assessment tax return.

When completing your return:

  • Enter the total CIS tax deducted by all contractors during the year.

  • Include all income received from CIS jobs.

  • Claim allowable business expenses, including the cost of materials.

HMRC will then calculate whether you have overpaid tax and issue a refund if applicable.

To prevent this from happening again, speak with your contractor and remind them that CIS deductions should apply only to the labour element of your invoice.

What about materials for limited companies under CIS

If you operate through a limited company, the same rules apply for materials, but the process for reclaiming CIS deductions differs.

Your company must:

  • Report all CIS deductions on your monthly Employer Payment Summary (EPS).

  • Offset the deductions against PAYE and National Insurance liabilities.

If your company still has CIS tax left over after the end of the tax year, you can apply to HMRC for a refund.

Accurate record keeping of material costs is essential for both compliance and ensuring your company’s Corporation Tax calculations are correct.

Can I claim for materials I already owned

You can claim for materials you already owned if they were used or consumed on a specific job. The value you claim should reflect their cost to you, not their resale value.

For example, if you use leftover tiles from another project, you can claim the original purchase cost proportionate to the amount used. Keep records or receipts to support this claim in case HMRC asks for evidence.

What not to include as materials

HMRC is strict about what counts as materials for CIS purposes. You cannot claim for:

  • Tools or equipment that you keep after the job.

  • Travel expenses unrelated to transporting materials.

  • Personal protective equipment (PPE) or clothing.

  • Office or administration costs.

  • Subcontractor labour (this is labour, not materials).

These items may still be allowable business expenses for tax purposes but cannot be excluded from CIS deductions as materials.

How an accountant can help

CIS rules can be complex, especially when it comes to distinguishing between labour, materials, and other costs. An accountant can help you by:

  • Reviewing your invoices to ensure materials are listed correctly.

  • Advising on how to record expenses for CIS and tax purposes.

  • Helping reclaim overpaid CIS tax.

  • Managing your Self Assessment or company PAYE submissions.

Professional advice ensures you stay compliant with HMRC and receive full credit for your legitimate costs.

Final thoughts

As a CIS subcontractor, you can and should claim for materials supplied on a job, as tax should only be deducted from your labour costs. To do this correctly, clearly itemise materials on your invoices, keep all receipts, and make sure your contractor understands how to apply CIS deductions.

If you believe too much tax has been taken, you can reclaim it when filing your Self Assessment return or through your company’s PAYE account. By keeping accurate records and seeking professional advice when needed, you can ensure you are paid fairly for your work and materials while staying compliant with HMRC regulations.