At Autumn Budget 2017, the government announced that the assessment time limit for income tax, capital gains tax and inheritance tax, in cases of mistakes or non-deliberate offshore tax non-compliance, will be increased to at least 12 years after the end of the relevant tax year or relevant period.

Where there is deliberate non-compliant behaviour, the current time limit of 20 years will remain, whether offshore matters are involved or not. HMRC says the additional time is needed to address situations where the current assessment time limits of four and six years are not sufficient to establish the facts and determine and assess the amount of tax due.