CG51891 - Share reorganisations: apportionment of cost: general
The main rule in TCGA92/S129 is that you make the apportionment at the date of disposal of any of the shares in the new holding. The instructions on Section 129 are at CG51892+. However, Section 129 does not apply if the new holding includes more than one class of share or debenture and any of the shares or debentures are quoted. In this case you make the apportionment at the date of the reorganisation, TCGA92/S130. The instructions on Section 130 are at CG51965+.