Unison said the delay was frustrating for staff who expected the money before Christmas.
“These are low-paid workers, the vast majority of them women, who keep hospitals running by doing vital tasks under huge pressure,” said the union’s northern regional secretary Clare Williams.
“It’s unacceptable that they were left in limbo for months.
“Staff have always prioritised patient care and now they can continue to do this knowing their work is properly valued.”
In 2024 the trust put healthcare assistants on a higher wage band, backdated to July 2023.
Unison said this did not go far enough and were locked in a dispute until an agreement was reached in September.
The row saw staff threaten to walk out and a protest held outside Darlington Memorial last year.
Andrew Thacker, director of workforce at the trust said he hoped the development would provide “reassurance that all required national approvals” were completed.
“We recognise that this has been a frustrating and, at times, upsetting process for those colleagues affected,” he said.
He added payments are expected to be made in February subject to agreements between all parties being signed.
“We are working through arrangements and will confirm details as soon as possible,” Thacker said.