If you owe HMRC self-assessment tax, then you need to make sure it’s paid by 31 January 2019 to avoid interest and a late payment penalty.
Also, if your liability is over £1,000 then you may have to make payments on account towards your 2019 liability.
If you’re not sure how much you owe, call HMRC on 0300 200 3310 (0161 931 9070) with your National Insurance number and UTR to hand. Alternatively, you can check your account with HMRC online if you have set this up, and if you don’t why not set it up now? http://www.gateway.gov.uk/
There are many ways to pay your self-assessment tax liability, though online with your debit card or via online banking are the most popular.
For all payments you will need to enter your reference number – which will be your Unique Tax Reference number (UTR), which is 10 digits long and you will find on the top left corner of your tax return. You need to add a ‘K’ to the end of the this to get your reference number, so 0123456789K
For more details and the link to pay by card online, click here https://www.gov.uk/pay-self-assessment-tax-bill.