As the 31 January deadline looms London and UK CIS subcontractors deserve confident, compliant expense claims. This guide from Interface Accountancy shows you which CIS costs are safe to claim how to organise records and how to maximise your refund while staying HMRC compliant.
TL;DR
- You can claim legitimate business costs to reduce taxable profit and potentially increase your refund.
- Common safe expenses include tools, equipment, vehicle costs, PPE, insurance, training and phone/internet costs.
- Documentation is critical: keep receipts, invoices, mileage logs, and bank statements.
- CIS deductions (usually 20%) can exceed your final liability. Proper claims help ensure you get the right refund.
- Work with an accountant to avoid red flags. Interface Accountancy offers a free CIS expense review.
How to approach claiming CIS expenses step by step
- Identify all potential expense categories relevant to your CIS work tools, equipment, vehicle costs, PPE, clothing, insurance, training, communications, home office if applicable.
- Separate allowable business costs from personal spend note the business purpose and apportion costs where necessary.
- Collect and organise receipts, invoices, mileage logs and statements. Keep digital copies and back them up.
- Calculating each expense’s impact on your tax base reduces taxable profit using your accounting method.
- Review HMRC guidance for CIS and your trade to confirm eligibility. See HMRC CIS guidance.
- Complete the self assessment form accurately ensuring expenses are allocated to the correct boxes and categories.
- Submit by the 31 January deadline be aware of penalties if deadlines are missed.
- If unsure, book a free CIS expense review with Interface Accountancy to verify claims before submission.
What expenses can CIS subcontractors safely claim? Categories with quick guidance
Tools and equipment
Purchases for job performance are allowable, keep receipts and note the date and how the item relates to a CIS job.
Vehicle costs
Van running costs, fuel and insurance are claimable. Use actual costs or a simplified method with proper logs.
Travel and subsistence
Travel between sites and PPE or work clothing are eligible. Distinguish uniform or protective clothing from personal wear.
Insurance and professional indemnity
Business related insurance premiums and PI cover are deductible.
Training and qualifications
Courses directly tied to your CIS duties count. Keep invoices and certificates.
Communications
Mobile, internet and business calls used for work qualify as expenses.
Home office
If you work from home apportion a reasonable share of utilities and broadband to business use.
Subscriptions and memberships
Trade bodies or tools used for business purposes are deductible.
Accountant fees
Fees for preparing and filing CIS returns are eligible expenses.
Note: Always separate personal costs and ensure each item has a clear business justification.
Documentation and compliance what HMRC expects
- Receipts, invoices and itemised bills for each expense.
- Mileage logs or van records with date, purpose and miles.
- Bank or card statements showing payments.
- Timesheets or job records linking expenses to CIS work.
- Clear accounting entries with dates, vendors and categories.
- Digital copies are acceptable, keep backups and ensure legibility.
- Retain records for six years for HMRC review.
- If a receipt is missing, document the reason and seek substitute evidence.
Real life example
Use Case Sam, a London electrician, earns £42,000 gross. He claims £6,500 in allowable expenses tools £2,000 van costs £1,800 PPE £500; phone/internet £600; training £700; insurance £900.
Result CIS deductions can exceed his final liability, yielding a meaningful refund after expenses reduce taxable profit. Interface Accountancy helps by reviewing eligibility, ensuring correct categorisation and confirming documentation before filing to maximise refunds while staying compliant.
Takeaway Proper tracking and documentation can meaningfully boost refunds when backed by a specialist review.
FAQ
What expenses are generally safe to claim on a CIS self assessment?
Tools, equipment, vehicle costs, PPE, insurance, training and business communications tied to CIS work.
Are accountancy fees tax-deductible for CIS subcontractors?
Yes, if they relate to preparing your CIS return and keeping accounts compliant.
Can I claim home office costs for CIS work?
Yes, if you have a dedicated workspace and can apportion utilities to business use.
What records do I need to keep?
Receipts, mileage logs, bank statements, timesheets and evidence linking expenses to CIS work.
What happens if I miss the 31 January deadline?
Penalties may apply; late filings incur a minimum and can escalate with time.
How do expenses affect my CIS refund?
They reduce taxable profit, potentially lowering tax and increasing refund when CIS deductions exceed liability.
Should I claim every possible expense?
Only those with a clear business purpose and solid documentation.
How can Interface Accountancy help me now?
We offer a free CIS expense review to validate claims and guide filing.