A misplaced decimal has seen an NT public servant overpaid almost half a million dollars.

The Northern Territory auditor-general has revealed the worker was supposed to be paid $4,921.76, but actually received a whopping $492,176 paycheque.

“The cause of the overpayment was a combination of two different human errors, those being the erroneous initial data entry and a subsequent failure to adequately address [a system-generated alert],” the auditor-general's report stated.

The overpayment was one of 743 made by government departments in the NT between July 2017 to January 2018, totalling more than $1.6 million, with $767,000 yet to be paid back.

The worker repaid the $492,176 within a few weeks of receiving it. The auditor-general said the repayment would have happened sooner but the person had “to physically attend their bank in an urban centre to authorise the return of funds the NT Government”.

The Department of Corporate and Information Services said overpayments represent about 0.2 per cent of the 1.2 million payroll transactions it processes every year.

The Top End Health Service ($452,754) leads the table of government departments making overpayments, followed by the Department of Education ($376,749) and the NT Police Fire and Emergency Services ($157,114).

“My review of the data related to salary overpayments highlights the necessity for the entity to be vigilant at all times,” the auditor-general said.