Mistakes are easy to make, especially on your tax returns so can you amend them?
Making an error on a personal tax return is not uncommon and HMRC make provision for taxpayers to amend their tax return providing this is done within one year of the original filing deadline.
For example for a 15-16 tax return which had to be filed by the 31 January 2017 you have until 31 January 2018 to amend your tax return, as this is one year after the original online tax return filing deadline of 31 January 2017.
If you fall outside of the time limit for amending a tax return you need to write or speak to HMRC and they will assess the individual circumstances.
HMRC will certainly charge some interest on the late payment of this tax which should have been paid by 31 January 2017. Currently the interest charged by HMRC for late payment of tax stands at 2.75% per annum.
This could also have an effect on any payments on account that would have been calculated at the time of filing the original return.
You should also make sure that you pay the tax owed within 30 days of the date of filing of the amended tax return otherwise HMRC can issue a surcharge.
If the original error was a genuine mistake then there should be no penalty issued by HMRC.
This may not be the case if HMRC have already written to you investigating the tax return – there is more on the HMRC penalty regime here.
Assuming you filed the original tax return online using HMRC software then you can log back into your account and in your self-assessment account follow the options to amend your tax return for the appropriate tax year. Where tax return software has been used, there is normally the ability to amend a previously filed tax return.
Your accountant can help you out with this and liaise with HMRC on your behalf.