For 2008/09 and subsequent returns, paper forms filed after 31 October following the tax return year will normally trigger a maximum penalty of £100 per individual.
A tax return filed between 1 November and 31 January following the return year must be filed online to avoid a penalty being charged.
Where a tax return cannot be corrected and submitted online, or if an agent or taxpayer feels unable to apply a workaround and therefore files the return on paper, the £100 penalty will potentially apply if it is filed after 31 October.
HMRC will, however, accept that there was a reasonable excuse for failing to file the paper return on time, provided the taxpayer supplies the online filing error message and files the paper tax return without unreasonable delay.
Where the relevant software does not facilitate a printed error message, the taxpayer will need to supply the error code or the text reported by his software instead.
The error message, or details of its contents, should be submitted with the claim for reasonable excuse. There is a downloadable claim form for doing so.
Alternatively, the claim can be made in a letter attached to the paper tax return.
The Revenue says it will generally be possible to suppress the £100 penalty where the claim for reasonable excuse is received by 23 January.
The department adds that this date is a guideline rather than a cut off date. It will be reviewed periodically to see if it can be moved closer to 31 January.