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HMRC internal manual

Self Assessment Manual

Returns: filing paper returns: 31 October deadline: late filed paper returns and subsequent penalties when filed online

If a paper tax return is filed late, it is not possible to avoid a penalty by filing a further tax return online before 31 January. The first return to be registered on the SA computer system will be treated as the original return. Only in exceptional circumstances where the online return reaches our systems before the paper return will a penalty not be charged. This will result in an entry on work list W024, as a duplicate return and it will be necessary to write to the customer. Please also see the guidance on unsatisfactory returns at SAM120590.