UK Payments on Account Explained 2026: 31 January & 31 July HMRC Bill

Short answer: Under Section 59A of the Taxes Management Act 1970, uk payments on account explained means HMRC requires UK sole traders to make two advance installments each year (due 31 January and 31 July), each equal to 50% of your previous year’s Income Tax and Class 4 National Insurance bill. Payments on Account trigger whenever your last Self Assessment bill exceeded £1,000 unless 80% or more of your tax was already deducted at source via PAYE or 20% CIS.

⚡ Instant UK Sole Trader SA103 & CIS Tax Toolkit (2026): Calculate your 31 January and 31 July tax reserve in the Self-Employment Tax Calculator, save your first 5 SA103 tax estimates or invoices in the iCloud Web Workspace (5 Free Saves), check the UK Self Assessment & SA103 App Store Edition, or download Keel for iPhone on the App Store (uk-self-assessment) to track SA103S expenses, 45p/25p mileage, and 20% CIS statements offline. — click 🔗 Embed / CSV Template to export

Nothing shocks a newly self-employed UK sole trader quite like logging into their HMRC Government Gateway account in their first January, expecting to owe £4,600, and seeing a demand for £6,900 due on 31 January.

Here is uk payments on account explained in plain English under HMRC’s Payment on Account rules:

Why the first 31 January bill is 150%

Suppose you started trading on 6 April 2024 and your combined Income Tax and Class 4 National Insurance bill for the 2024/25 tax year comes to £4,600:

1. On 31 January 2026, you owe the full £4,600 for 2024/25 (your balancing payment).
2. Because £4,600 is over HMRC’s £1,000 threshold, HMRC assumes you will earn at least the same profit in 2025/26—which is already nine months underway by 31 January 2026! So HMRC adds your First Payment on Account of £2,300 (50% of £4,600) onto the same 31 January deadline, making £6,900 due at once.
3. On 31 July 2026, you pay the Second Payment on Account of £2,300.

Why CIS subcontractors are often exempt (The 80% Rule)

If you work mostly as a verified CIS subcontractor and contractors have already deducted 20% CIS tax at source covering 80% or more of your total tax liability, HMRC does not put you into Payments on Account.

Reducing Payments on Account (Form SA303) when work slows down

If you lost a contract, took parental leave, or bought a new work van under Annual Investment Allowance (AIA) so your current-year profit will be lower than last year’s, you can apply online or via Form SA303 to reduce your 31 January and 31 July Payments on Account. Only reduce them to what your real records show you will actually owe—if you reduce them too far, HMRC charges late-payment interest from the original due date on the difference.

How do the rules and numbers break down side by side?

Use this compliance and billing matrix when preparing your next quote, invoice, or tax return under HMRC Self Assessment Payments on Account (TMA 1970 s.59A):

Line Item / Compliance Scenario	Statutory Rule & Requirement	Worked Financial Impact (£)
31 January (First Year in Payments on Account)	100% of prior-year Balancing Payment + 50% First Payment on Account	You pay 150% of one year’s tax bill on a single day
31 July (Mid-Year Instalment)	50% Second Payment on Account toward current tax year	Clears the remaining half of your advance estimate
Next 31 January (Ongoing Cycle)	Any Balancing adjustment + 50% First POA for new year	Settles cleanly if your profits stayed steady
Exemption Triggers (£1,000 or 80% Rule)	Prior bill ≤£1,000 OR ≥80% paid at source (PAYE / CIS)	No Payments on Account required

How do you build these numbers into your pricing and cash flow?

Whether you are billing a £4,600 job or reconciling £2,300 in material and operating receipts, the difference between a profitable trade business and a cash-strapped one comes down to separating your money (net labour and margin) from money passing through your hands (materials, tax collected in trust, or statutory withholdings of £6,900).

Three practical habits keep your numbers clean all year:

1. Quote from your true loaded cost: Always account for material costs, compliance certificates, travel/permit charges, and overhead before adding your target profit margin.
2. State every statutory identifier on the first submission: Putting your required tax registration, licence number, and itemised scope on the initial PDF prevents accounts-payable clerks, strata managers, or main contractors from kicking the invoice back into a 30-day review queue.
3. File the supplier receipt under the job on the day of purchase: A thermal receipt photographed at the trade counter substantiates both your tax deduction and any material cost split on a £1,000 project.

For related guides in this region, see uk self employed tax guide, uk cis subcontractor invoice guide, and uk making tax digital sole traders.

How do you keep your quotes, invoices, and receipts sorted on site?

Keel is an iPhone app built for solo tradespeople, subcontractors, and sole traders who want to write estimates and PDF invoices in the van, photograph supplier receipts at the trade counter, and log business mileage—with no bank connection. Every quote, invoice, and receipt stays filed under the job on your device, ready to hand to your accountant as clean supporting records at tax time. Free to download on the App Store.

What step-by-step audit checklist should you run before filing in 2026?

When you review your books at the end of the quarter or tax year for uk payments on account explained, running a five-minute reconciliation between your issued client invoices, your supplier receipts, and your vehicle log prevents the most common audit adjustments:

1. Verify Sequential Invoice Numbering and Dates: Confirm that every completed job has a dated, sequentially numbered invoice showing the customer’s legal name, the site address, and an itemized split between trade labor and direct materials.
2. Match Material Receipts to High-Value Jobs: Whenever a project involves significant supply-house purchases, equipment rentals, or municipal permit fees, keep the photographed vendor receipt filed under that specific job so you can prove your direct cost basis and input tax treatment in seconds.
3. Cross-Check Statutory Registration Numbers: Make sure your active tax identifier, trade licence number, and workers’ compensation clearance reference are printed in your invoice template header so commercial accounts-payable teams never hold back a progress draw.
4. Separate Pass-Through Taxes and Withholdings from Net Profit: Whether your invoices involve sales tax, GST/HST, VAT, or statutory construction withholdings, treat tax collected in trust separately from your operating margin so quarterly remittances never catch your bank account short.

How should you archive job records and receipts for multi-year retention?

Tax and licensing authorities require self-employed contractors to retain complete supporting records—including numbered invoices, paid supplier dockets, mileage logs, and permit sign-offs—for three to seven years depending on the jurisdiction. Exporting a clean PDF and CSV archive at the end of every quarter ensures your records remain accessible even if you change phones or trucks.

Frequently asked questions

What happens if I omit a required registration or tax breakdown on my invoice?

Under HMRC Self Assessment Payments on Account (TMA 1970 s.59A), omitting mandatory fields—such as your tax identifier, licence number, or the separation between labour and materials—can cause commercial payers to withhold higher statutory deduction rates, reject the invoice for payment, or disallow input tax claims during an audit.

Can I issue an amended invoice if the scope or tax treatment changes before payment?

Yes. If you need to correct a tax rate, add an approved variation, or split materials from labour before the customer settles the bill, credit or void the original document reference in your sequential invoice log and issue a clearly numbered replacement invoice so both sets of books match.

Do digital photos of trade counter receipts satisfy tax audit requirements?

Yes. Tax authorities in the UK (HMRC), Australia (ATO), Canada (CRA), and the US (IRS) accept clear digital photographs or scans of original itemised paper receipts, provided the vendor name, date, item descriptions, total amount, and tax component remain completely legible for the statutory retention period (5 years in Australia, 5+ years after the 31 January filing deadline in the UK, and 6 years in Canada).

Should I include my payment terms and bank or card details on every quote and invoice?

Always. State the exact calendar due date (such as “Due on completion” or “Due within 7 days”) alongside your bank transfer details and a QR payment link on the PDF so the customer can settle the balance on the spot while you are still on site. Keeping your sequential client invoices, dated supplier receipts, and compliance records filed under each job ensures you can verify these numbers immediately during any customer or tax review.

How does Keel help with year-end tax preparation without connecting to my bank?

Because every invoice you issue, every supplier receipt you photograph, and every work journey you log is already categorised by job and date on your iPhone, you do not need a third-party cloud aggregator reading your personal bank statement. At the end of the tax year, you simply export your organised income, expense, and mileage pack for your accountant.

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This guide provides general information for self-employed operators as of 2026 and is not formal tax or legal advice. Always verify current thresholds and statutory requirements with HMRC Self Assessment Payments on Account (TMA 1970 s.59A) or a qualified accountant.