Paying your Self Assessment tax should be a planned step, not a stressful deadline — with the right advice, it becomes routine and worry-free.
– Nigel Holland BA (Hons) FCA
1. What is the Self Assessment tax bill?
Your Self Assessment bill is the total tax and National Insurance you owe personally, based on your tax return. It can include:
-
-
Income tax
-
Class 2 and Class 4 National Insurance (for the self-employed)
-
Capital Gains Tax
-
Student loan repayments (if applicable)
-
Once you have filed your tax return, HMRC calculates how much you owe (or you calculate it via the online system) and shows this in your HMRC online account.
2. When do you have to pay?
There are two main types of payments:
-
-
Balancing payment
-
Payments on account
-
Typical key dates (UK tax year 6 April to 5 April):
-
-
31 January –
-
Deadline to file your online tax return for the previous tax year
-
Deadline to pay your balancing payment
-
Deadline to pay your first payment on account for the current tax year (if due)
-
-
31 July –
-
Deadline to pay your second payment on account (if due)
-
-
If HMRC charges you payments on account, each instalment is normally half of last year’s tax bill (excluding Capital Gains Tax and student loans).
If the final calculation for the year shows that you still owe more than the payments on account you have made, you will also have a top-up balancing payment due by 31 January.
3. Check what you owe before you pay
Before paying, always:
-
-
Log in to your HMRC online account
-
Go to Self Assessment
-
Check:
-
Total owed
-
How much is due now
-
Any payments already made
-
Whether you have payments on account
-
-
Make sure the figure you’re paying matches your latest calculation and HMRC’s records.
4. Ways to pay Self Assessment
HMRC offers several payment options. Electronic methods are usually fastest and safest.
4.1 Bank transfer (Faster Payments, CHAPS, Bacs)
You can pay directly from your bank using:
-
-
Faster Payments (online or mobile banking)
-
CHAPS
-
Bacs
-
Use the HMRC Self Assessment bank details given in your online account or on gov.uk, and quote your 11-character Self Assessment payment reference (this is your 10-digit UTR plus the letter K at the end).
Example: 1234567890K
Timing:
-
-
Faster Payments / CHAPS – usually same day or next working day
-
Bacs – usually takes three working days
-
Always allow enough time for the payment to reach HMRC by the deadline.
4.2 Online or telephone banking
Most banks let you pay “HMRC Self Assessment” directly:
-
-
Log in to online banking or your banking app
-
Choose “Pay a business or organisation” (wording varies)
-
Search for “HMRC Self Assessment”
-
Enter your UTR + K as the reference (exactly)
-
Confirm the amount and send
-
Keep a record of the payment confirmation for your files.
4.3 Debit card or corporate credit card
You can also pay online by:
-
-
Debit card
-
Corporate credit card
-
via the HMRC card payment service. You’ll need:
-
-
Your 11-character Self Assessment reference (UTR + K)
-
Card details
-
The amount to pay
-
Note: Personal credit cards are generally not accepted for tax payments.
4.4 Direct Debit
You can set up a Direct Debit through your HMRC online account:
-
-
Log in to your HMRC online account
-
Select Self Assessment
-
Choose “Set up a Direct Debit”
-
Follow the steps to authorise payment
-
You can either set up a one-off payment or, in some cases, use Direct Debit each time you pay. Make sure the Direct Debit is set up in time so the funds clear by the deadline.
4.5 At your bank or by post (cheque)
These are now less common, but still possible for some taxpayers:
-
-
Pay at your bank using a payslip from HMRC
-
Post a cheque with your payslip to HMRC
-
Cheques should be made payable to:
“HM Revenue & Customs only” followed by your UTR.
These methods are slower, so allow extra time to reach HMRC by the due date.
5. Using the correct payment reference
Your payment reference is critical. If it’s wrong, HMRC may not match the payment to your account correctly.
For Self Assessment, your reference should be:
-
-
Your 10-digit Unique Taxpayer Reference (UTR)
-
Followed by the letter K
-
Example: 1234567890K
Always double-check:
-
-
No spaces
-
No extra characters
-
Same UTR that appears on your tax return and HMRC letters
-
6. Time needed for payments to clear
Approximate clearing times (once you’ve made the payment):
-
-
Faster Payments: usually same day or next working day
-
CHAPS: same working day if made before your bank’s cut-off
-
Bacs: about 3 working days
-
Cheque by post: can take a week or more including post and processing
-
If the deadline falls on a weekend or bank holiday, the funds must reach HMRC by the last working day before that date.
7. What if you can’t pay in full?
If you know you can’t pay on time:
-
-
Do not ignore it – penalties and interest will build up
-
Log in to your HMRC online account – in many cases you can set up a Time To Pay arrangement online for smaller debts
-
For larger or more complex situations, you may need to speak to HMRC to agree a payment plan
-
A Time To Pay arrangement does not cancel interest, but it can help you avoid more serious action if you stick to the agreed terms.
8. Penalties and interest for late payment
If you pay your Self Assessment tax late, HMRC may charge:
-
-
Interest on the outstanding amount from the day after the due date
-
Late payment penalties if the tax remains unpaid after certain time periods (for example, 30 days, 6 months, 12 months)
-
There are also separate penalties for late filing of the tax return itself, even if no tax is due. It’s always best to file and pay as early as possible.
9. Good habits to manage Self Assessment smoothly
-
-
Keep bookkeeping up to date during the year
-
Use software (such as KashFlow or similar) to track income, expenses, and tax estimates
-
File your tax return early rather than leaving it until January
-
Check your HMRC online account well before the deadline
-
Set up calendar reminders for 31 January and 31 July
-
Keep a record of every payment made (bank confirmation, screenshots, etc.)
-
These simple habits reduce stress, avoid last-minute panics, and help you plan your cash flow.
10. Bringing it all together
Paying your Self Assessment bill is straightforward when:
-
-
You know exactly what you owe
-
You have the right reference (UTR + K)
-
You use a payment method that clears in time
-
Once your systems are in place, it becomes a predictable part of your financial routine rather than a yearly panic.
If you want help estimating your tax, planning your payments, or setting up better records so Self Assessment becomes easier each year, you can build that into your overall tax and business planning.
