What a CIS subcontractor bookkeeping template actually has to do
Four running records cover every figure a CIS sole trader needs for a complete self-assessment return: an income ledger, an expenses ledger, a mileage log and a deduction statement tracker. Between them they carry roughly twenty columns. Everything else that gets added to a subcontractor's spreadsheet over the years is decoration.
The columns below are the working structure, set out as tables you can copy straight into a spreadsheet or use as a checklist against whatever you already run. The order matters less than the fact that each one exists, because the two most expensive bookkeeping failures in construction are both structural: recording the net payment instead of the gross invoice, and recording a single job total instead of a labour and materials split.
This is a subcontractor template. If you pay other subcontractors yourself, you are a contractor as well and have a CIS300 monthly filing obligation on top of everything here, which a spreadsheet cannot discharge.
Sheet 1: the CIS income and deduction ledger
One row per payment received, not per invoice raised. Payment date is what determines the tax month a CIS deduction falls into, and it is what your contractor's monthly return is built on.
| Column | What goes in it | Why it earns its place |
|---|---|---|
| Date paid | Date the money reached your account | Determines the tax month and the tax year the deduction belongs to |
| Contractor | Name of the paying contractor | Groups the year by contractor for statement reconciliation |
| Invoice number | Your reference | Ties the row back to the invoice and the job |
| Labour (£) | Labour element, excluding VAT | This is the only figure the CIS deduction should be applied to |
| Materials (£) | Materials you supplied, at cost, excluding VAT | Excluded from the deduction base. Also a box 17 expense |
| Other charges (£) | Plant hire, consumables, recharges | Treatment varies. Keep separate so it can be classified correctly |
| Net invoice total (£) | Labour plus materials plus other | Feeds your turnover figure |
| VAT (£) | VAT charged, or zero under the reverse charge | Never part of the CIS deduction base |
| CIS rate | 0%, 20% or 30% | Flags anything deducted at the wrong rate immediately |
| CIS deducted (£) | Amount withheld | Totals to box 81 on the SA103F. This is the refund |
| Net received (£) | Amount actually banked | Reconciles the row to your bank statement |
| Statement received | Yes, no, or date chased | Turns a January panic into a monthly two-minute check |
The rate column does more work than it looks. A registered subcontractor should see 20%, an unregistered one 30%, and a subcontractor with gross payment status 0%. If a 30% row appears in a ledger that is otherwise 20%, a contractor has failed to verify you or has verified you incorrectly, and every week that goes unnoticed is another 10% of your labour income sitting with HMRC.
The labour and materials columns are what stop over-deduction. If you invoice a single total, a contractor can apply the deduction to the whole amount, materials included. Our guide to splitting labour and materials on CIS invoices covers what counts as materials and how to structure the invoice, and the CIS subcontractor invoice template gives you invoice layouts that already carry the split in the right places, including reverse charge and non-VAT-registered versions.
Sheet 2: the expenses ledger, mapped to the self-assessment boxes
The single most useful thing you can do with an expenses sheet is give it a category column whose values are the actual SA103F expense box headings. Categorise as you enter, and the return fills itself. Categorise in January from a carrier bag, and things get missed.
| Column | What goes in it |
|---|---|
| Date | Date of the receipt or invoice, not the date you paid the card bill |
| Supplier | Merchant, wholesaler, insurer, training provider |
| Description | Enough detail to justify the claim two years later |
| Amount (£) | Net of VAT if you are VAT registered, gross if you are not |
| Business use % | 100% for most trade spending, lower for mixed-use phone or broadband |
| Claimed (£) | Amount multiplied by business use percentage |
| Category | The SA103F expense box heading (see below) |
| Job reference | Which job the cost relates to, where it relates to one |
| Receipt held | Photo filename, or a link if the receipt sits in software |
The category values to use are the expense headings on the SA103F self-employment pages. On the 2026 form (the 2025/26 return) they run from box 17 to box 30, and the ones that carry real weight for construction trades are:
| Box | SA103F heading | What a subcontractor puts here |
|---|---|---|
| 17 | Cost of goods bought for resale or goods used | Materials bought for jobs |
| 18 | Construction industry, payments to subcontractors | Anyone you paid under CIS yourself |
| 19 | Wages, salaries and other staff costs | Employed labour and casual help |
| 20 | Car, van and travel expenses | Mileage claim or actual van costs, parking, congestion charge |
| 21 | Rent, rates, power and insurance costs | Public liability, tools cover, yard or lock-up rent |
| 22 | Repairs and maintenance of property and equipment | Tool servicing and repairs |
| 23 | Phone, fax, stationery and other office costs | Mobile at business-use percentage, broadband share, software |
| 24 | Advertising and business entertainment costs | Van signwriting, listings, website |
| 25 | Interest on bank and other loans | Interest on van or equipment finance, not the capital repayments |
| 26 | Bank, credit card and other financial charges | Business account fees, card processing fees |
| 27 | Irrecoverable debts written off | Invoices a contractor never paid and never will |
| 28 | Accountancy, legal and other professional fees | Accountancy fees, contract advice |
| 30 | Other business expenses | PPE, small tools, trade subscriptions, CSCS renewal, training |
Two practical notes. Box numbers move between the short pages (SA103S) and the full pages, and occasionally between years, so match on the heading rather than memorising a number. And if your annual turnover was below £90,000, HMRC lets you enter one total in box 31 instead of splitting across boxes 17 to 30. That is a filing shortcut only. The categorised records still have to exist, and the act of categorising is what shows you the empty rows where a genuine claim should be.
What belongs in each category, and the awkward edges (subsistence, workwear, use of home, capital items above the small-tools line), are covered in full in our guide to allowable expenses for CIS subcontractors.
Sheet 3: the mileage log behind your biggest expenses claim
Mileage is usually the largest single deduction a subcontractor makes and the one most often lost, because HMRC expects a contemporaneous journey record and a reconstruction from memory does not qualify. Five columns, filled in weekly.
| Column | Example entry |
|---|---|
| Date | 14/09/2026 |
| Start point | Home |
| Destination | Site, Wellington Road development, plot 12 |
| Purpose | Second fix, Barrett contract |
| Miles | 34 |
Add a running total and a rate calculation at the foot. From 6 April 2026 the Approved Mileage Allowance Payments rate is 55p per mile for the first 10,000 business miles in a car or van and 25p per mile thereafter, up from 45p. On 14,000 business miles that is (10,000 x 55p) + (4,000 x 25p) = £5,500 + £1,000 = £6,500. Any template still calculating at 45p is understating the claim by £1,000 across the first 10,000 miles.
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Sheet 4: the CIS deduction statement tracker
The fourth sheet is the smallest and prevents the most delay. One row per contractor per tax month, with a column for the deduction figure on their statement and a column for the deduction figure in your income ledger. Where the two disagree, the difference gets chased in the same month rather than the following January.
Contractors must issue a written payment and deduction statement within 14 days of the end of each tax month in which a deduction was made. Repayments most often stall because a subcontractor's box 81 total does not reconcile to what contractors reported on their monthly returns. Chasing a missing statement in October is a phone call. Chasing it in February, after filing, is a repayment sitting on hold. Retention periods and what HMRC asks for in a compliance check are set out in our CIS record keeping guide.
How the columns feed your self-assessment return and refund
Take a sole trader joiner with 2026/27 figures pulled straight from the four sheets above.
| Line | Source column | Amount |
|---|---|---|
| Labour invoiced | Sheet 1, labour | £42,000 |
| Materials invoiced | Sheet 1, materials | £6,000 |
| Turnover | Sheet 1, net invoice total | £48,000 |
| Materials cost (box 17) | Sheet 2 | £6,000 |
| Mileage, 12,000 miles (box 20) | Sheet 3 | £6,000 |
| Insurance (box 21) | Sheet 2 | £600 |
| Phone and office (box 23) | Sheet 2 | £360 |
| Accountancy (box 28) | Sheet 2 | £480 |
| PPE, small tools, CSCS (box 30) | Sheet 2 | £1,400 |
| Total expenses | Sheet 2 and 3 | £14,840 |
| Taxable profit | Calculated | £33,160 |
| Personal allowance | 2026/27 | -£12,570 |
| Income tax at 20% | On £20,590 | £4,118 |
| Class 4 NIC at 6% | On £20,590 | £1,235 |
| Total liability | Calculated | £5,353 |
| CIS deducted at 20% on labour | Sheet 1, box 81 | £8,400 |
| Repayment due | Calculated | £3,047 |
The mileage figure alone, £6,000 from a five-column log, is worth roughly £1,560 of the repayment once income tax and Class 4 are counted. That is what the columns are for. Note also that the deduction applies to the £42,000 of labour and not to the £48,000 total, because materials sit outside the CIS deduction base.
To test your own numbers before you build anything, run them through the CIS self assessment calculator, which applies the 2026/27 rates and shows the repayment moving as each expense category is added.
MTD-proofing the habit before the thresholds reach you
Making Tax Digital for Income Tax phases in by qualifying income, measured from the return two tax years earlier:
| Qualifying income | Tax year measured | You must comply from |
|---|---|---|
| Over £50,000 | 2024/25 | 6 April 2026 |
| Over £30,000 | 2025/26 | 6 April 2027 |
| Over £20,000 | 2026/27 | 6 April 2028 |
For a CIS subcontractor, qualifying income means gross turnover before CIS deductions, not the net figure that reached the bank. A joiner banking £48,000 after 20% deductions on £60,000 of labour is measured on £60,000. That distinction catches people out every year and is covered in detail in our guide to MTD for Income Tax and CIS.
A spreadsheet stops being sufficient on its own once MTD applies to you, because quarterly updates have to be submitted from compatible software or through bridging software that reads your sheet. The column structure above is what makes that transition trivial: every field maps onto a field in QuickBooks, Xero, FreeAgent or Sage without restructuring anything. The trade-offs between the two approaches are set out in our comparison of spreadsheets versus accounting software for CIS workers.
Four sheets, about twenty columns, ten minutes a week. That is the whole of CIS bookkeeping for a sole trader subcontractor, and it is the difference between a repayment claim built on evidence and one built on estimates. The gross-not-net rule and the labour-materials split are the two structural points to get right on day one, because neither can be reconstructed later from a bank statement.
If your records for previous years are thinner than they should be, our CIS refund service reconstructs the position from contractor statements and bank records, files the returns and pursues the repayment.