The government has delayed the deadline for most businesses to start using a new system for managing exports.
Customs Declaration Service (CDS) is replacing the current Customs Handling of Import and Export Freight (CHIEF) service.
The new software, which is already being used for imports, was originally due to come into force in March but its introduction was then delayed until 30 November.
The government has now announced a new "phased approach" with "selected high-volume" exporters still needing to switch by 30 November, and all other businesses needing to move to CDS for exports by 30 March 2024.
HM Revenue & Customs said it had made the change "after listening to feedback from industry".
Anna Doherty, senior trade and customs specialist at the Institute of Export and International Trade, commented:
"The new timeline gives government and businesses breathing space to properly prepare for the CDS migration as issues remain with the new system, including functionalities around creating declarations for inventory-linked locations.
"Exporters which use services of multiple agents for their customs declarations may also find themselves in a position where they have a mix of CHIEF and CDS entries, similarly as we experienced with the roll out of CDS for imports."
The CDS announcement follows delays to other changes.