The deadline for paying your self-assessment tax for the 2019/20 tax year is the 31st January 2021. For those that took up the 31st July 2020 payment on account deferral this tax bill could be more than expected.
As this has been a challenging year for many, if you think you will struggle to make payment please do not just ignore the tax due. HMRC are being very lenient so you need to contact them, I lay out below your options.
Tax bill is less than £30k
This will be relevant to the majority. If this is the case then you may be able to pay in monthly instalments.  This can be done by following the link below and setting up a payment plan. You just need your government gateway login details to do so.
You can also call the HMRC helpline on 0300 200 3822, I would suggest calling early on in the day as they do tend to get very busy so you may experience long waiting times. The helpline is open from 8am to 6pm so I would suggest calling as soon after 8am as possible.
Tax Bill over £30k
You should still be able to arrange a payment plan although this cannot be done by using the link above, you will instead need to call HMRC on 0300 200 3822. 
Interest charged on late payment
Please note that HMRC have stated they will charge late payment interest on any tax due so the above arrangements will come with a cost. At present an interest rate of 2.6% is applied to any payments made after the due date of the 31st January 2021.
I hope the above was helpful and if you have any questions please get in touch.
Daniel Routcliffe
Tel: 01392 360008