Your income tax return will fall due on the 31 January AFTER the end of the relevant tax year. So the tax due for the year of 6 April 2014 to 5 April 2015 will be due on 31 January 2016.
When does the tax year run from and to?
The Income Tax year always runs from 6 April to 5 April. It’s an odd day but has always been this way. The tax year applies to all individuals in the UK, though not to Companies.
So when you hear talk of the 2015/16 tax year what that means is the period of 6 April 2015 to 5 April 2016.
The tax year is important because this is the period for which you have to declare income to HMRC on your income tax return, also known as the self-assessment tax return or SA100.
When do I need to submit my tax return
Tax returns are due on 31 January along with any payments due.
So taking the 2015/16 year, the tax year ends on 5 April 2016 and you have to pay tax and submit the return by the end of the next January, ie. 31 January 2017.
What about Payments on Account
If you are required to make Payments on Account then you may also have to pay tax on 31 July 2017 for the 2016/17 income tax year.
Read more about Payments on Account.