VCM93050 - CVS: deferral relief: amount of deferred gain revived
You should check the other guidance available on GOV.UK from HMRC as Brexit updates to those pages are being prioritised before manuals.
Where a chargeable event occurs in relation to any shares (in relation to which there has not been a previous chargeable event) a chargeable gain accrues to the investing company at the time of the event. The amount of this revived gain is equal to the amount of the deferred gain that is attributed to the shares in question on a pro rata basis.
An investing company subscribes £100,000 for 200,000 shares for which it obtains investment relief. Of this expenditure £40,000 is set against a gain of £40,000 and £20,000 is set against a gain of £20,000. These gains are deferred. The deferred amounts of £40,000 and £20,000 are each attributed to all the shares. If the company disposes of 50,000 of the shares (1/4 of the total 200,000) at a time when no investment relief attributable to them has been withdrawn, the disposal will cause chargeable gains of £10,000 and £5,000 (1/4 of each deferred gain) to be revived.