You must pay the balance of any tax you owe by 31 January following the end of the tax year. This is also the date when you may have to pay the first of two ‘payments on account’ towards your next tax bill.
The January payment deadline is the same for both paper and online returns and there are very few exceptions. As an example, the deadline may be later if HMRC sends you the letter, telling you to complete a return, after 31 October. In this case you’ll usually need to send in the return and pay the tax due within three months of the date of the letter.
This is the date when you may have to pay the second ‘payment on account’ towards your next tax bill.
If you don’t pay any tax you owe for the previous tax year on time you may be charged interest. The longer you delay, the more you’ll have to pay. So it’s important to pay the tax as soon as you can.
More about Interest and penalties if you don’t pay your tax on time
You can check how much tax you owe by logging into HMRC’s Online Self Assessment service. You’ll be able to see a statement of what you have paid and what you owe or are owed. Or if you’ve already signed up for the Business Tax Dashboard you can also view your liabilities and payments there.