Herts county council and Serco have apologised after a payroll mistake led to school staff receiving bills for unpaid tax.

The problem arose when Serco, which provides payroll services for the council, sent Her Majesty’s Revenue and Customs (HMRC) information about the earnings for 15,000 school staff for the 2017/18 tax year.

It is believed Serco sent information for 13 months, rather than the usual 12, causing teachers to be sent bills for unpaid tax as high as £10,000.

General manager for citizen services at Serco UK Jacqui Richards said: “Following advice from HMRC, we resubmitted a previously rejected electronic file for employee monthly pay.

“This incorrectly resulted in duplicate figures being registered by HMRC for employees for one month.

“As soon as we identified this issue we immediately got in touch with HMRC to correct the error and contacted schools to reassure their employees that no money was due.

“We apologise to all those who incorrectly received claims from the HMRC and want to reassure them that we have amended our procedures to ensure that this issue is not repeated.”

The bills were sent in October 2018 and staff at 400 schools in Hertfordshire were given five days to pay, or face action from HMRC.

Serco has a contract with the council to process all their financial transactions and run services such as security, payroll, HR and children’s contact until 2021.

A county council spokesperson said: “We were made aware of this issue by Serco and are confident that it has been resolved and none of the county council employees were financially impacted by this error.

“In line with Serco, we apologise for any inconvenience caused.”