Being paid for days you did not work or mistakenly promoted to a higher pay band must sound like the stuff of dreams. But that is what happened to hundreds of teachers in Lancashire.
Payroll blunders have led to school staff receiving up to pound;1,700 in extra wages, with some teaching assistants being paid double their salary and supply teachers being asked to work for free in September to make up for being overpaid last term.
The NAHT heads' union said it has received complaints from more than 300 school leaders whose staff have been overpaid to the tune of hundreds of thousands of pounds.
The catalogue of errors also includes some teachers not receiving what they were owed, which has left them struggling to make ends meet, according to union officials.
Around 600 maintained schools in Lancashire have their payrolls managed by One Connect, a joint venture set up by Lancashire County Council and BT. While the authority claimed that the deal would save it more than pound;1 million a year, schools say they have been overwhelmed by mistakes resulting from the payment system.
Evidence seen by TES shows that four classroom teachers have been asked to hand back between pound;1,200 and pound;1,700 each. The affected employees are expected to sort out the resulting tax, National Insurance and pension complications themselves.
Despite One Connect being at fault for the errors, heads said that they have been left to pick up the pieces, with many expected to play the role of "bailiffs" and arrange for the overpayments to be recouped.
Sam Uddin, the NUT's Lancashire secretary, said that some teachers have been left struggling to make ends meet due to late payment of wages, while others have been accidentally moved up or down the pay scale as a result of administrative errors. There have also been several incidents of short- term contracts being terminated on the wrong date.
"The problem is that (One Connect) assumed there was one kind of teacher and one kind of employee," he said. "When they see something that isn't quite `normal', they appear to make it up as they go along."
Les Turner, Lancashire secretary for the NAHT, said that the branch has been "snowed under" with complaints from members after the new payment system was introduced last year.
"It's a complete nightmare," he said. "They said they were having some teething troubles, but they are dragging on a little bit - it's over a year on. The child is now in infancy and the problems keep coming back."
Mr Turner added that One Connect should be responsible for recouping overpayments, not school leaders. "If I am paying for a service, I expect that service to be provided. If they fail to provide it, it's up to them to sort it out, it's not up to the customer."
One school leader discovered that all of his teachers who worked hourly overtime were only being paid for 42 minutes out of each additional hour.
Heather Bragg, a solicitor at legal firm Browne Jacobson, said that teachers who have been overpaid are obliged by law to return the money, either in a lump sum or in instalments over a set period of time. "If a teacher said they had already spent the money, they wouldn't have a leg to stand on," she said.
A spokeswoman for One Connect said that schools that have encountered problems "should raise the matter to seek an immediate resolution".
"One Connect is supporting schools to ensure that a quality service continues to be provided across its extensive schools customer base," she added.
What school leaders have reported to the NAHT:
"What a joke . My bursar is NOT happy!"
"The system cannot deal with two changes at once, for example temporary contract to permanent plus changing hours."
"The system is far too complicated to work effectively . It has been a nightmare."