Retroactive nomination of main home?

[cathw]

I bought Property A in 2010 as my main home and Property B, closer to my workplace and much less expensive, in 2012. I went back and forth between the two, keeping most of my possessions in Property A. In 2014 I sold Property B and informed HMRC that Property A would be again my main residence. There was a small taxable gain on Property B, but I paid no CGT, taking it as my main residence for the two years 2012-2014, and assuming I would stay in Property A for a very long time, rendering any eventual CGT on it negligible.
Unfortunately, I decided to sell Property A in 2016 and there is a considerable gain. When the sale completes can I go back and change my nomination to make Property A my main home for 6 years continuously 2010-2016 and pay any CGT due on the sale of property B in 2014?

[maths]

In 2014 I sold Property B and informed HMRC that Property A would be again my main residence.

Not quite sure what this means. It suggests that you elected for Property B to be your main residence effectively from 2012.
If so, then Property A cannot qualify as a sole or main residence for the period 2012 to 2014.

Property A would accordingly appear to qualify as your sole residence for 2010 to 2012 and again from 2014 to 2016.

[cathw]

Thank you, that would be one interpretation, but doesn''t the law allow for a change to the nomination whenever the ownership configuration changes, which it will when I sell Property A and buy a new Property C? The question is whether it would allow a change of this type.
Presumably I could have made the change within the two year window after selling Property B, but just missed the cutoff.

[maths]

A change of circumstances may permit a new election as to the main residence for a period; any election having to be made within 2 years of the relevant date.

However, on the sale of A and the acquisition of C (assuming B and C are then both residences) it will not be then possible to argue (by making a second election) that A was the main residence for the period 2010 to 2014 having previously elected B as the main residence for 2012 to 2014.

[cathw]

Thank you. It sounds like I missed the cutoff by 6 weeks by not changing right after the sale of B in August 2014.