How to pay my Self Assessment tax bill online

Understand what you’re paying and why it matters

Paying your Self Assessment tax bill online is one of those jobs that feels intimidating until you’ve done it once. After that, it becomes a predictable routine: check what you owe, choose a payment method, send the money, and keep proof for your records. This guide walks you through the online payment options in plain English, with practical steps and “watch-outs” so you don’t get caught by avoidable mistakes like using the wrong reference, paying to the wrong account, or missing a deadline.

In the UK, Self Assessment is HMRC’s system for collecting Income Tax and National Insurance (where applicable) from people whose tax isn’t fully collected through PAYE. That includes many self-employed people, landlords, company directors with untaxed income, and anyone with certain kinds of income or circumstances that require a tax return. Your “tax bill” is the amount HMRC says you owe after you submit your tax return (or after HMRC calculates it based on the return you filed). You can usually see that balance inside your HMRC online account.

Before you pay, it helps to know the key parts of the bill:

Balancing payment: the amount due for the tax year you’ve just reported.

Payments on account: advance payments towards the next tax year’s bill (often two instalments, usually due in January and July). Not everyone has these, and the amount can change.

Interest and penalties: extra charges if you pay late or file late (or if adjustments create additional amounts due after the deadline).

When you pay online, you’re typically paying one combined balance. The online system will allocate it appropriately as long as you use the correct reference. That reference is the single most important detail to get right.

Before you start: what you need ready

You can save yourself a lot of stress by getting these things lined up before you click anything:

1) Your HMRC online account access. If you already use Self Assessment online, you’ll have a Government Gateway user ID and password (or another sign-in method). If you don’t, set it up in advance, because creating access can take time if you need identity checks.

2) Your Unique Taxpayer Reference (UTR). This is a 10-digit number used to identify your Self Assessment record. You’ll find it on letters from HMRC, in your online account, or on previous tax returns.

3) Your bill amount and due dates. Your online account shows what you owe. If you’re paying close to the deadline, aim to pay earlier than the last day to allow for bank processing times.

4) A payment method. Common online options include paying by debit card, by bank transfer (online banking/Faster Payments/CHAPS), or by Direct Debit (if set up). Each method has different processing times and potential fees.

5) The correct payment reference. For Self Assessment, you’ll generally use your UTR followed by a letter “K” (for example: 1234567890K). Think of it like the label on the parcel. If you leave it off or type it wrong, HMRC may not match the payment to your account quickly.

Step 1: check your balance in your HMRC online account

Start by confirming what HMRC thinks you owe right now. This matters because the balance can change if you’ve recently filed a return, amended it, or if HMRC has added penalties or interest. It also matters if you’re trying to pay only part of what’s due (for example, paying the balancing payment now and budgeting for the second payment on account later).

Inside your Self Assessment area, you’ll typically see a summary that includes:

Total amount due and the payment deadline.

A breakdown of what the balance includes (balancing payment, payments on account, penalties, etc.).

Sometimes a separate section for what you’ve already paid and what’s still outstanding.

If the amount looks unexpected, don’t guess. It’s better to pause and review your calculation or check whether payments on account have been applied. If you filed your return very recently, allow time for the account to update, but do not rely on “it will probably fix itself” if you are near a deadline. If needed, you can still make a payment to reduce interest and then reconcile later.

Step 2: choose the best online payment method

“Paying online” can mean a few different things. The right method depends on how quickly you need the payment to reach HMRC, whether you’re happy to store bank details for future use, and whether you want to pay in one go or spread it out (where possible).

Option A: pay by debit card online

Paying by debit card is usually the simplest, most familiar option. You log in, enter the amount, enter your card details, and submit. It’s typically quick, and you get immediate confirmation on screen. If you like the reassurance of seeing a confirmation page right away, this is often the easiest route.

How it works in practice:

1) Go to your HMRC Self Assessment payment page (usually accessible after signing in).

2) Choose to pay by card.

3) Enter the amount and your Self Assessment reference (check it carefully).

4) Enter your debit card details and complete any bank security prompts.

5) Save or screenshot the confirmation.

Watch-outs:

Some banks apply daily online spending limits; large tax bills can trigger those limits. If your payment is declined, check your limit and consider splitting the payment into multiple transactions (if allowed) or use bank transfer instead.

Credit card payments are not always available for Self Assessment in the same way debit card payments are, and where available they may involve fees. If you prefer credit card for cashflow reasons, confirm availability and costs first, and be realistic: interest on the card can easily outweigh any perceived benefit.

Option B: pay by bank transfer using online banking (Faster Payments, CHAPS, or Bacs)

Paying by bank transfer is a solid option if you’re paying a large amount or if you want to schedule the payment through your own bank’s app. It also gives you direct control over the reference. Many people use Faster Payments because it’s quick, but you still need to be careful about cut-off times and whether your bank treats it as instant or same-day.

How it works in practice:

1) Find the correct HMRC bank account details for Self Assessment.

2) In your banking app/online banking, create a new payee.

3) Enter the sort code and account number exactly as provided.

4) Enter your payment reference (usually your UTR plus “K”).

5) Send the amount and keep the transaction confirmation.

Watch-outs:

HMRC has different bank account details for different taxes. Self Assessment is not the same as PAYE, VAT, Corporation Tax, or Capital Gains Tax. Always ensure you’re paying to the Self Assessment account.

The reference is crucial. If you omit it or use the wrong one, HMRC may not allocate the payment correctly, which can lead to “late payment” letters even though you did pay.

If you pay from a business account, that’s fine, but the reference still needs to match the taxpayer’s Self Assessment account. The payer name doesn’t reliably allocate the payment; the reference does.

Option C: pay by Direct Debit online

Direct Debit can be convenient, especially if you want to avoid re-entering bank details or if you prefer HMRC to collect on a specified date. However, Direct Debits usually take time to set up and are not ideal for last-minute payments right before a deadline.

How it works in practice:

1) Log into your HMRC online account and choose to pay by Direct Debit.

2) Set up the Direct Debit mandate with your bank det