Why your tax bill might be a lot bigger than you expected

[lizbarclaybiz]

The UK’s payments on account system catches a lot of new sole traders by surprise.

Payments on account are advance payments towards your next Self Assessment tax bill (in this case for the year 25/26). You pay them on top of any tax you owe for the previous (24/25) tax year.

HMRC uses payments on account to help spread the cost of your tax across the year rather than collecting it all at once.
They apply mainly to:
• self employed people
• landlords
• anyone with untaxed income

1. They are based on last year’s tax bill
   HMRC assumes your income next year will be similar to the previous year.
   So each payment on account is half of your previous year’s tax bill.
2. You make two instalments
   • 31 January
   • 31 July
3. You may also need a “balancing payment”
   If your actual tax bill ends up higher than the two instalments you’ve already paid, you pay the difference the following 31 January.
   If you paid too much HMRC will refund you.

You won’t be asked to make payments on account if either:
• your last tax bill was £1,000 or less, or
• 80% or more of your tax was already collected at source (e.g., PAYE).

If your tax bill last year was £3,000, HMRC will ask you to pay:
• £1,500 on 31 January
• £1,500 on 31 July
towards next year’s bill.
If your actual bill ends up higher, you pay the extra as a balancing payment the following January.

It’s particularly tough to find the additional money to pay on account if you’re fairly recently self-employed and weren’t expecting it. You may have put aside money to cover tax on the amount you were earning but not to cover the additional amount. HMRC doesn’t automatically require new sole traders to pay tax on account in their first year. The rules above apply,
You will have to make Payments on Account if both of these apply:

1. Your tax bill for the year is more than £1,000, after subtracting any tax already deducted at source (e.g., PAYE).
2. Less than 80% of your total tax was collected at source.
   If those conditions apply, HMRC will ask you to make:
   • First payment on account: 31 January
   • Second payment on account: 31 July
   Each is normally 50% of your previous year’s tax bill.
   You won’t have to make Payments on Account if:
   • Your tax bill is £1,000 or less, or
   • More than 80% of your tax was already deducted (e.g., you still have PAYE employment), or
   • HMRC decides your first year’s liability is too low to trigger the system.
   This is very common for brand new sole traders whose first year is part time, low income, or mixed with PAYE work.
   If:
   You start self employment in 2025/26 and owe £600 in tax.
   → No payments on account.
   You owe £2,500, but you also have PAYE employment that covered 85% of your total tax.
   → No payments on account.
   You owe £2,500, and PAYE only covered 20%.
   → Yes. You will have to make payments on account.

If you’re unsure whether you’ll cross the £1,000 threshold, try to set aside 20–30% of your profits so you’re covered whether payments on account apply or not.
This is an example where a qualified accountant can keep you right. You may worry that the fees will be too expensive but accountants will keep you safe and probably save you money in the long run. Check their qualifications. Unqualified people calling themselves accountants have been known to give poor advice.