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Tax Year 2020/21: All The Key Dates You Need To Know And Plan For

It’s an understatement to say it’s been a difficult year. With so much going on due to Covid-19, its easy to forget tax deadlines for filing and tax payments.

Late filing will almost always result in penalties, and no one needs to be paying more than they have to right now.

This blog gives you all the dates for the 2020/21 UK tax year, including filing dates for accounts and key taxes as well as a brief guide to whats required.

For information related to coronavirus and paying taxes, plus funding support, visit our coronavirus hub


Key dates for the UK tax year 2020/21

6 April 2020
The first day of the 2020/21 tax year

The start of the new tax year, which often means changes to tax rates and sometimes laws and regulations.

It’s always a good time to sit down with your accountant and plan for the following tax year 2020/21 dates, and assess how any changes to tax rates will affect you.

If you’ve not already switched over to accounting and tax software, this will make submitting your return significantly easier – as well as facilitating a better working relationship with your accountant. 

31 July 2020
Second payment on account for Income Tax

If you file a Self Assessment tax return, you’ll also be required to make 2 payments to HMRC in January and July. These are known as payments on account and are basically advance payments to cover the tax payable for the upcoming year.

Each payment is based on 50% of the previous years tax bill.

So, if your total tax bill was £4,000 this means you’d pay £2,000 in January and again in July.

As this is based on the previous year, it’s worth mentioning if you expect profits and tax to fall in the UK tax year 2020/21 due to Covid-19. You can contact HMRC to get these payments reduced.  

5 October 2020
Deadline for Self assessment registration

If you’ve become self-employed, become a company director or have received additional income in the last tax year (2019/20), but have yet to let HMRC aware of your change in employment status or income, you must register for Self Assessment by 5 October. You will need to register online on the GOV.UK website to receive your 10-digit Unique Taxpayer Reference.

Failure to do so can result in some hefty fines, as much as 30% of the tax owed.

31 October 2020
Deadline for individuals to submit paper Self Assessment tax returns if requesting underpayments of tax of £3,000 or less to be collected through 2021/22 PAYE code. 

If you have income from PAYE and a tax bill of less than £3,000 and want this to be collected by wage deductions over 12 months from April 2021, you must submit your paper tax return by 31 October 2020.

If you’d prefer to do this online, you have slightly longer to submit your tax return (30 December 2020).

31 October 2020
Self Assessment tax return submission deadline for paper returns for 2019/20

If you’ve earned any income outside of PAYE tax then you’ll have to submit a Self Assessment tax return.

The deadline for paper submission is 31 October, although these days the vast majority of returns are now filed online (31 January deadline) as paper is being phased out.

30 December 2020
Deadline for individuals to submit online Self Assessment tax returns if requesting underpayments of tax of £3,000 or less to be collected through 2021/22 PAYE code. 

You can use the HMRC online portal to register and file Self Assessment tax returns online.

Here you can request tax if less than £3,000 to be collected from your PAYE 2020/21 coding.

Check out the website for more information about paying your Self Assessment tax bill through your tax code.

31 December 2020
Filing of accounts deadline for March year ends. 

The most common company year end is 31 March, if this is you this means you need to file your company accounts by 31 December 2020. Fines start at £150 for late filing but do escalate quickly the later it gets. 

1 January 2021
Corporation Tax due date for all companies with 31 March year ends.

Happy New Year! And what better way to start it then with a tax payment!

For the majority of companies this is 1 January (all companies with a year end 31 March 2020)

If you don’t have a 31 March year end, your Corporation Tax payment is due 9 months and 1 day after your year end. You can use our Corporation Tax calculator to work out a rough guide as to how much you’ll owe. 

31 January 2021
Online filing deadline for 2019/20 Self Assessment tax return.

The big one. This is the filing deadline for Self Assessment tax returns.

If you’ve earned any income outside of PAYE tax this means you’ll need to submit at tax return. This declares what you’ve earned for the tax year 2020/21, and what tax you need to pay. You can use our self-employed tax calculator to work out how much you’ll owe. 

Late filing penalties start at £100 and again escalate if over three months.

31 January 2021
Balancing payments and payments on account due.

In addition to the payment of tax for the current year, there will be a payment on account, which is effectively 50% of the tax paid in advance.

There are some circumstances in which a payment on account will not be due. If your tax bill for the previous year was less than £1,000 after PAYE or other deductions at source, you won’t need to make a payment on account. Similarly, no payment on account will be due if, in the previous tax year, 80% or more of your tax was deducted at source.

31 March 2021
Corporation Tax filing deadlines for companies with a 31 March 2020 year end.

Corporation Tax return filing deadline for those companies with a 31 March 2020 filing deadline. The return needs to be submitted within 12 months of the year end (even though the payment was due 9 months after year end). 

31 March 2021
Deferred VAT repayment.

Any businesses that deferred VAT for balances due between March and June 2020 now need to start repaying them. This can be done in 11 instalments over the year. To pay in instalments you have to opt in, which will be available to do early 2021.


Accounting software can massively help to make your life easier when it comes to filing your tax return. Here are some options worth checking out: 


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Stuart Hurst

Stuart Hurst is a Manchester accountant and Director at Accounts and Legal.

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