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.
