Self Assessment payment dates · multiple return years
Payments on Account Calculator
Calculate the balancing payment, first payment on account and second payment on account from your Income Tax, Class 4 National Insurance and tax already deducted.
Capital Gains Tax and student-loan amounts are kept in the balancing payment but excluded from the next payments on account.
Use figures from the tax calculation and statement
Calculate your January and July Self Assessment payments
Enter the assessed liabilities before tax deducted at source. Enter payments on account already made separately so they are credited only once.
- Income Tax and Class 4
- £8,000.00
- Relevant amount
- £6,000.00
- Tax deducted proportion
- 25.00%
- Payments already made
- £4,800.00
Do payments on account arise?
Payment breakdown
Payments on account are indicated because the relevant amount is at least £1,000 and no more than 80% was deducted at source.
Estimate only. Your HMRC Self Assessment statement determines the actual amounts, credits and due dates.
Direct answer
How are payments on account calculated?
HMRC normally starts with the previous year’s Income Tax and Class 4 National Insurance and deducts qualifying tax paid at source. The amount left is the relevant amount. If payments on account are required, each instalment is normally 50% of that figure.
Capital Gains Tax and student-loan repayments do not form part of the relevant amount. They are instead paid through the balancing payment due after the tax year.
The first instalment for the following year is normally due on the same 31 January date as the balancing payment. The second is normally due on 31 July. You can also return to the UK tax calculators directory.
The two statutory exceptions
When payments on account are not normally required
Both tests are considered using the completed year’s figures.
The relevant amount is below £1,000
If Income Tax and Class 4 remaining after tax deducted at source is less than £1,000, HMRC does not normally create payments on account for the next year.
More than 80% was paid outside Self Assessment
Payments are not normally required where more than 80% of the assessed amount was already collected at source, such as through PAYE or qualifying CIS deductions.
Read HMRC’s payments on account guidance and the detailed Self Assessment legal framework.
Follow the year each payment belongs to
Self Assessment payment timeline
The date a payment is made and the tax year it funds are different. That is why a January bill can contain two separate liabilities.
- 31 January during the tax year
First payment on account
An advance payment towards that tax year.
- 31 July after the tax year
Second payment on account
The second advance payment towards the same year.
- 31 January after the tax year
Balancing payment
The remaining liability after both advance payments and tax deducted.
- The same 31 January
Next first payment on account
The first advance payment towards the following tax year.
Worked example
Why the January amount can be larger than expected
Suppose the completed year shows £7,000 Income Tax, £1,000 Class 4 NIC and £2,000 deducted at source. The relevant amount is £6,000, so the next payments on account are normally £3,000 each.
- Completed-year liability including £500 CGT
- £8,500
- Less tax deducted and £4,800 prior instalments
- £6,800
- Balancing payment
- £1,700
- Plus next first instalment
- £3,000
- Amount due in January
- £4,700
Claiming a reduction
Reduce payments only from a reasonable full-year estimate
A reduction may be appropriate where profits or other income will fall, reliefs will increase or more tax will be deducted at source.
The estimate should consider the following year’s total Income Tax and Class 4 liability, not only the income source that has fallen.
Keep the accounts, forecasts and tax workings supporting the amount claimed.
HMRC can charge interest from the original due dates if the reduced instalments prove insufficient.
A claim can normally be made online or using form SA303.
See HMRC’s official claim-to-reduce guidance.
Check the source figures
What to have beside you when using the calculator
SA302 or calculation summary
Use Income Tax and Class 4 before the credits shown separately.
Payments and allocations
Confirm what HMRC has actually credited to the selected year.
Tax deducted at source
Use deductions belonging to the tax year being calculated.
CGT and student loan
Keep these outside the relevant amount but within the balancing figure.
Common questions
Payments on account calculator questions
Are payments on account an extra tax charge?
No. They are advance payments towards the following year’s Income Tax and Class 4 National Insurance. They are credited when that year’s final balancing payment is calculated.
Why are two amounts due on 31 January?
The January bill can contain the balancing payment for the completed year and the first payment on account for the following year. They relate to different tax years.
Does Capital Gains Tax increase payments on account?
No. Capital Gains Tax is excluded from the payment-on-account computation. It can still increase the balancing payment due on 31 January.
Are student-loan repayments included?
A Self Assessment student-loan amount can form part of the balancing payment, but it is excluded when calculating payments on account.
What if I have paid more than the calculator shows?
The calculation may indicate a potential overpayment, but check how HMRC allocated every payment. A credit can be held against another liability or tax year.
Can I reduce only the July payment?
A valid reduction claim adjusts the payments based on the expected relevant liability. The HMRC statement will show the revised amounts and any credit or balance.
Confidential enquiry
Need the HMRC statement checked?
Tell us the return year, the amounts shown and what appears unclear. Do not send your UTR, National Insurance number, payment reference or bank details through this form.
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