With the paper deadline for submitting the 2011/2012 Tax Return passing last October, the final chance to submit a Tax Return, without penalties, is the online filing deadline of 31st January 2013.
HMRC provide an online service to submit a Tax Return and providing the taxpayer has login details, they can submit on the same day - However, if they do not they need to get registered by this Monday, 21st January. The seven day period to get registered will be cutting the deadline close.
For people who have lost their ID or password, they will also need to get these replaced by the 21st.
If the 31st January deadline is missed, the first stage penalty is a £100 fine. This applies even if their is no tax due or tax due is paid on time.
Further penalties may apply the longer a Tax Return is not submitted, at three, six and twelve month stages.