The HMRC Agent Update for self-assessment contains an odd warning about submitting a tax return as an amendment, when the original return has not been submitted. When this happens the “amended return” cannot be processed, which may result in a late filing penalty.

HMRC says is it receiving large numbers of “amended” returns filed online this season, which indicates there is a common trap that many accountants are falling into. You would think that tax software would be intelligent enough to prevent this from happening, but not all software products have this fail-safe mechanism.

For example, it is quite easy to click the “amended” box in the Taxcalc or Taxfiler software when completing a tax return, in which case the return will be submitted as an amended return, even if no original version of that return has been filed.

It is sensible that the HMRC computer system should not accept amended returns if an original version of that tax return has not been logged as received. There is a real risk of hackers submitting amended returns and diverting tax repayments to their own bank accounts, so HMRC has to be particularly careful about accepting any amendments to returns.