Analogue vs Digital
While the UK online deadline is January 31, the paper filing deadline is **October 31**. However, HMRC is increasingly making digital filing mandatory for certain income types. For US expats, using a digital service allows you to calculate your UK tax liability early, which is helpful for US tax planning.
Strategic Data Expansion 2026.4
The £100 Late Fee
Missing the paper deadline results in an automatic £100 penalty, even if no tax is due. LSI keywords include 'SA100,' 'Government Gateway,' and 'HMRC App.' In 2026, Making Tax Digital (MTD) starts becoming relevant for landlords and sole traders with income over £50,000.