This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Oil Taxation Manual

Capital gains: non residents: administration and payment of tax

The onus for reporting the gains generally rests on the non-resident disposer. In the event of default on payment of tax assessed by virtue of TCGA92\S276 or CTA10\S1170 by a non-resident, FA73\Sch15\Para4 makes the relevant licence holder(s) liable for any tax unpaid more than 30 days after the due and payable date where the gains have accrued from exploration and exploitation rights connected with activities authorised by the UK licence.

You can find further information about the administration procedures for recovery of tax at OT45000.