CG52583 - Share exchange: effect of TCGA92/S135: computation
If a shareholder has separate Section 104 holdings of shares in Company X and Company Y, and both these companies are later taken over by Company Z in exchange for the issue of its own shares, all the Z shares issued in exchange will form a single pool.
If however the shares in Company Y had been acquired in, say, 1980 the Company Z shares would remain as two separate pools in the hands of the shareholder - as a Section 104 holding (reflecting the Company X shares), and a 1982 holding (reflecting the Company Y shares).