More than £130 million is still tied up in Atol-protected credit notes and vouchers, the CAA has said.
The authority has urged holidaymakers to get them spent before the Atol protection they carry runs out on 30 September next year.
From 20 December, firms will no longer be able to issue Atol-protected credit notes.
The scheme was introduced in the early stages of the pandemic to address the initial refund crisis in travel as almost all travel globally was suspended.
Credit notes allowed firms to defer refunding customers and clients when cash was tight while ensuring that money retained the protection with which it was booked.
Michael Budge, head of Atol at the CAA, said: “With more than £130 million of Atol refund credit notes yet to be redeemed, and international travel opening up again, we want to remind consumers to redeem any unused credits to make sure they do not lose out.
“Refund credit notes have been a fantastic tool to reassure consumers and support the industry. The decision to end the scheme reflects the changing of international travel restrictions with significantly increased demand from consumers over recent months due to the opening up of more destinations.”
The CAA will not consider any claims for unredeemed credit notes held with firms that fail after 30 September.
In total, £131.7 million worth of cash tied up in credit notes remains unspent, the BBC reports citing the CAA.
Last month, credit card firm Capital One estimated there was likely to have been nearly £5 billion issued to consumers in refund vouchers owing to cancelled holidays, trips and events.