The UK tax year is usually between 6 April to 5 April in a 12 month period for sending in your tax return and making payments. The tax department can impose penalties and surcharges if you miss or are late with regard to this deadline.

If you send in a paper tax return, it must reach HMRC by midnight on 31 October. The deadline for paper tax returns is only later than 31 October if you receive the notice to file your tax return after the 31 July - in this case you will have three months from the date you receive the notice if you want to send in a paper return. The same is applicable if you are completing a paper return because there is no software available to file your tax return online or you have been told by HMRC that you are not allowed to file online. Under such circumstances you will have until 31 January to send in your return.

If you send your tax return online, it must reach HMRC by midnight on 31 January. The deadline is earlier if you owe tax of less than £2,000 and you want HMRC to collect it by reducing your Pay as You Earn (PAYE) tax code next year. In this case you need to send your tax return online by 30 December instead. HMRC will try to amend your code number, but it's not always possible, and you may still have to make a payment instead by 31 January.

The deadline is only later than 31 January if you received the notice to file your tax return after 31 October. You will then have three months from the date you receive the notice to send your return online. HMRC does not issue receipts for paper tax returns. However if you file online you'll get an on-screen acknowledgment once they've received your return.

If HMRC receives your tax return after the filing deadline, you'll be charged an automatic £100 penalty. If a Partnership Tax Return is late there's a £100 penalty for each partner. If a Trust and Estate Tax Return is late there's a £100 charge to the trust or estate. You will not have to pay a penalty if you have a reasonable excuse for missing the deadline. There's no hard and fast rule on this but usually the delay must be completely due to an exceptional or major unexpected event that's outside your control.

Some examples of what HMRC may consider as a reasonable excuse are documents being lost through theft, fire or flood that you can not replace in time, life-threatening illness, for example a heart attack that prevents you dealing with your tax affairs, the death of a partner shortly before the filing date. You may need to show that you had taken steps to prepare the return before this happened, industrial action by Royal Mail over a lengthy period of time, or issues with the online filing service, where no work-round was available - you'll need to provide the error message you received.

If you have got a reasonable excuse you can ask for a penalty to be reconsidered. HMRC will look carefully at the information you provide and any other evidence that is available. You should make any claim as soon as possible instead of waiting until you receive the penalty.

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