Domicile: election by non-UK domiciled spouse or civil partner: election ceasing to have effect
Once an election is made, it cannot be revoked, IHTA84/S267ZB(9). However, once a person who has made an election has ceased to be resident in the UK for Income Tax purposes for a period of four successive tax years beginning any time after the election has been made, the election will cease to have effect at the end of the fourth tax year, IHTA84/S267ZB(10).
This approach is in line with the position where a taxpayer is deemed domiciled in the UK under IHTA84/S267(1)(b). To shake off that deemed domicile, they need to be resident outside the UK for four years.
Where the person making the election is resident in the UK, they must cease to be resident for four successive tax years. Unless they cease to be resident right at the end of the tax year, they will effectively need to be non-resident for a minimum of four tax years before the election ceases to have effect. For example, if a person ceases to be resident in the UK on 31 December 2015, the election will not cease to have effect until the end of 2019/20 - four successive tax years being 2016/17 to 2019/20 inclusive.
Contrast this with the position where a person making the election is resident outside the UK. At the time of making the election, they are already non-resident, so the year in which the election is made will count as the first year of non-residence. So following the example above, 2015/16 is the first year of non residence, so the election will cease to have effect at the end of 2018/19.