Barts and the London Trust referred 248 of its staff to debt collectors after overpaying them by a total of £1m last year, documents obtained by HSJ reveal.

Reports released under the Freedom of Information Act said “most” overpayments went unrecovered and in November 2011 more than half of the cases were over a year old.

The trust - which has subsequently become part of Barts Health Trust - had an annual staff bill of approximately £399m.

An October 2012 report to the newly-appointed human resources director Michael Pantlin from his outgoing predecessor said the trust had also made overpayments of £1m to staff in 2010-11.

A July 2012 report of the London Audit Consortium, a body made up of NHS finance professionals from across the capital, said there was only “limited” assurance that the trust “had the mechanisms in place to address [its] long-term problem with high levels of salary overpayments”.

It said 82 per cent of overpayments were because of late notification of the payroll department that staff had left or changed their hours.

The report said: “Audit testing found an instance where the change made to pay was over three years late. This late change led to an overpayment of over £126,000 gross pay for the employee who has since left the trust. The doctor was paid a banding supplement for on-call duties [£4,000 a month) but since July 2007, had no responsibilities for such duties.”

After the finance department raised the issue with the head of human resources in May 2011 an invoice for repayment was issued and a debt collection agency instructed.

The overpayment is now being repaid at £500 a month, or a 21-year period.

One of the reports recommended overpayments to existing staff should be recovered by deductions from their salary. It said: “Where the overpayment is relatively large compared with salary received, deductions should still be made so that a level of net salary of, for example, 60 per cent remains.”

A spokeswoman for the trust said: “Barts Health is currently piloting a new electronic system which will enable managers to provide payroll with the most up-to-date information in the most timely way.  

“We rigorously pursue all salary overpayments and are confident that this new additional measure will help further to avoid their occurence.”