This information is based on government guidance retrieved January 2020.
https://www.gov.uk/pay-self-assessment-tax-bill/
When do I need to pay?
We recommend you make payments as soon as you can, the dates below are deadlines.
You maybe required to make two advance payments ‘on account’ as a way of spreading your tax bill. These are based on your previous year.
31st January – balancing payment for tax for the previous year.
– first payment on account.
31 July – second payment on account (not required for all).
Your payment method must clear by the deadline in order to avoid surcharges. Make sure you leave enough time depending on the method you wish to use. The quickest way to pay HMRC is online.
How can I pay?
Payment reference for bank transfers is your 10-digit Unique Taxpayer Reference (UTR) followed by the letter ‘K’.
How much should I pay?
We provided you with the amount to pay after we filed your tax return on your behalf. Our covering letter for your final tax calculation states the amount clearly for you.
This may have been provided to you by email. If so, your final tax calculation will also be available for your reference in your secure Document Portal.