If one half of a married couple transfers some shares to the other half, does that somehow "reset" (for capital gains purposes) the "book cost" of those shares, or not?
This might be best illustrated by a hypothetical example case:
Mrs X made a £20,000 investment in 10,000 racy AIM shares at £2/share (outside of any ISA or SIPP wrapper) and a few years later they're now worth £8/share and she wants to take some gains to rebalance her portfolio, but without incurring any CGT. Assuming the CGT allowance is £11,300...
Obviously she can sell 1883 of the shares herself for a gain of 1883*(8-2)=£11,298 (for simplicity, I'm ignoring complications like being allowed to account for dealing costs and stamp duty etc).
But what if she and Mr X also want to make use of his otherwise unused CGT allowance? If she has her broker transfer another 1883 of the shares to Mr X's account and he disposes of them, is his CGT calculation also 1883*(8-2)=£11,298... or does the transfer somehow change the book cost so far as Mr X's calculation is concerned (because he got them "for free" maybe, in which case he can only safely dispose of 1412 shares 1412*(8-0)=£11,296)?