Last year, almost 450,000 online returns were filed on the last day with the 37,500 being filed between 4-5pm.
HMRC said the only time the deadline is not applicable is a letter about completing a tax return was not received until after 31 October 2012.
HMRC does not accept late returns where taxpayers claim they do not have enough money to pay the tax due, say they have failed to receive a reminder or late receipt of online activation codes or passwords.
If tax returns are submitted late there is a £100 initial penalty to pay and escalating penalties that apply after three months.
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The initial penalty still applies even if tax returns are a day late, there is no tax to pay or all the tax owed has already been paid.
After three months, a fine of £10 is added per day to the maximum of £900.
After six months, a fine of £300 or five per cent of the tax due is payable then after a year a further £300 fine or five per cent of the tax due will be added to the bill.
If a person has a valid reason for missing the deadline such as death of a partner, life-threatening illness or documents lost due to theft or flood then they can appeal to HMRC.
Last year, a record 9.4m tax returns were returned by the deadline, the first time more than nine million people had filed on time, and some 7.7m of these were filed online.

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