It's one of the smallest symbols on the keyboard, but when it comes to salary payments, a decimal point is a very big deal.

Key points: NT auditor-general identified 743 salary overpayments

NT auditor-general identified 743 salary overpayments Incorrect payments totalled more than $1.6 million

Incorrect payments totalled more than $1.6 million One worker accidentally received $492,176

The Northern Territory auditor-general has revealed one public servant was accidentally overpaid almost half a million dollars in a single transaction last year.

The worker was supposed to receive $4,921.76, but an incorrectly-placed decimal point saw their bank account swell overnight by $492,176.

"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 bungle was one of 743 overpayments made by government departments in the NT between July 2017 to January 2018.

The incorrect payments totalled more than $1.6 million, with $767,000 yet to be paid back.

In the case of the $492,176 overpayment, the worker repaid the money four weeks later.

The auditor-general noted the repayment would have happened sooner had the worker not been based in a remote area.

"[The worker] needed to physically attend their bank in an urban centre to authorise the return of funds the NT Government," the report said.

In response to the report, the Department of Corporate and Information Services said it processes 1.2 million payroll transactions annually, with overpayments representing about 0.2 per cent of the total.

The department said it had enacted several system enhancements to prevent large overpayments occurring in the future.

The Top End Health Service ($452,754) topped the list of government departments where overpayments were made.

The Department of Education ($376,749) and the NT Police Fire and Emergency Services ($157,114) were next on the overpayments list.

The auditor-general said: "My review of the data related to salary overpayments highlights the necessity for the entity to be vigilant at all times."