The parcel carrier DPD has resumed its road service from the U.K. to the European Union after resolving customs clearance problems caused by post-Brexit administration rules. The U.K. left the single market on Dec. 31, 2020.

The company had suspended operations in the first week of the month and planned to start again on Jan. 13. However, continued confusion over incorrectly completed paperwork saw the pause continue until Jan. 16.

There were also problems due to an upgrade to the government’s Computerised Transit System (NCTS) which meant it could not validate all packages.

DPD said a fifth of cross-channel parcels had incomplete or incorrect paperwork.

Her Majesty’s Revenue & Customs (HMRC), the government agency responsible, had “overcome initial issues with their system and DPD is now in a position to recommence its road service for EU bound deliveries” the delivery firm said in a statement.

“All DPD International Air services have been continuously available and remain so.”

Problems with the NCTS and lack of awareness over regulatory requirements by consumers have heightened concerns that some firms will stop exports to the U.K. There are also worries that delays will increase as freight traffic ramps up after the quieter post-Christmas period and when Covid-19 restrictions are lifted.

New rules since Jan. 1 mean suppliers who send parcels containing goods valued at £135 (€151.7-$184.4) or less to the U.K. are responsible for paying any import value-added tax that is due – effectively collecting tax for HMRC.

The British media reported that e-commerce customers have also complained about the extra charges along with higher delivery fees to cover the extra paperwork with an increasing number returning rather than paying up.