Tax due on 31 January 2021
Don't overpay
The payment due under self-assessment on 31 January 2021 will include the first payment on account ( POA ) for 2020/21. That is computed at 50% of the amount due for 2019/20 UNLESS you apply to reduce it. For many people their income for 2020/21 will be less, if not much less, than for 2019/20. Thus, the tax liability for 2020/21 will be much lower than that for 2019/20. If you estimate the tax due for 2020/21 you can then apply for the POAs to be reduced accordingly. That can be applied for with the Tax Return 2020 or filed separately on a form SA303 if the Tax Return 2020 has already been filed.
If you use an accountant to file your Tax Returns, or have already done so, then he or she should be doing this for you - just check that they have.
Do not overpay!