The apportionment may be undertaken by an independent person qualified to make such a valuation or the taxpayer themselves, based on the relevant facts of the transaction.
Gall unigolyn annibynnol sy'n gymwys i wneud hynny brisio'r dosraniad neu gall y trethdalwr ei hun wneud hyn, ar sail ffeithiau perthnasol y trafodiad.