401(k)

I am a retired UK resident taxpayer. I spent a few years working with a US employer with whom I have a 401(k) retirement savings plan. I plan to cash this in, either by a single lump payment this year or by a series of lump sum payments over a 10-year period, starting this year. I understand that under Article 17.2 of the US-UK Double Tax Treaty, these lump payments will be taxable in the US. I also understand that they will be taxable in the UK but that I will be entitled to Foreign Tax Credit Relief for the US tax paid. My question, in respect of UK tax is – will I be entitled to avail of the tax treatment applicable to lump sums paid out of funds built up in overseas employer-financed retirement benefits schemes (EFRBS) prior to 6th April 2017? If so, I had approximately 4 years’ service with the US company prior to 6th April 2017 and I paid into the 401(k) over that entire period. Would I be entitled to 100% relief on the value of my 401(k) as of 5th April 2017, with 100% being the “appropriate fraction” calculated using the formula F/R, where ‘F’ is the period of pre-6 April 2017 reckonable foreign service and ‘R’ is the period of pre-6 April 2017 reckonable service?

Hi,
Please refer to:
PTM110000 - International
Thank you.