Christmas has come early for more than 300 primary care trust workers. They have been told they need not repay an average of £600 paid to them by mistake over the past three-and-a-half years.

Birmingham East and North PCT blames an inputting error at its payroll provider, University Hospital Birmingham foundation trust. When staff moved to Agenda for Change grades, 331 were entered into the payroll system one incremental point higher than the PCT had advised, it says.

Many have now left, been promoted, or reached the top of their pay grade - but 92 are still being paid at the wrong rate. The PCT has decided not to reduce anyone's pay until after Christmas. 'These staff are from all staff groups across the PCT and are not limited to a specific area or staff type,' said director of resources Jonathan Tringham. 'All 92 will be moved to their correct salary from February 2008.'

The trust said it would try to reclaim the estimated£200,000 cost of overpayment from University Hospital Birmingham, which is investigating the problem.