Pablo Olivares pleaded guilty to criminal offences, including two counts of forgery and three counts of theft, and was sentenced in a Brisbane court on Monday morning.

It came after the Department of Home Affairs and Australian Commission for Law Enforcement Integrity began investigating the former Australian Border Force officer when his supervisor noticed discrepancies on his credit card transactions.

The joint investigation found Olivares had made 134 cash withdrawals, several hotel bookings and rented a car, all without authorisation, on his corporate credit card between mid-2016 and mid-2017.

Forged medical certificates and falsified statutory declarations submitted by Olivares were also uncovered in the investigation.

Integrity commissioner Jaala Hinchliffe said his actions were not compatible with the work border force officials were expected to undertake.

"Providing false documents and forging signatures is a deliberate act of dishonesty, which is incompatible with the impartial exercise of an officer's powers, authorities, duties or functions," she said.

"The former ABF officer used his position to obtain a financial benefit and cause a detriment by defrauding the Commonwealth.

"Mr Olivares deliberately used his official powers and discretions for an improper purpose in numerous instances."

He will now face two-and-a-half years in jail and be forced to pay back $93,898.75.

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The integrity commission is expected to absorbed into a larger anti-corruption body after the federal government announced its plans to establish the Commonwealth Integrity Commission late last year.

The new body would have a total of 172 staff at full capacity, absorbing existing staff from the law enforcement integrity body.

ACLEI oversees nine agencies, including Home Affairs, AFP, AUSTRAC and the ATO, after its jurisdiction was expanded to include a number of financial regulatory agencies.

The law enforcement watchdog said it saw a substantial increase in corruption notifications last year related to the Department of Home Affairs.

In its annual report last year it said it had received 172 notifications of potential corruption with 167 of those relating to bodies under the Department of Home Affairs umbrella.

Of the 167 notices, 100 of those fell under "Home Affairs", which includes the Australian Border Force (ABF), with a further 63 relating to the Australian Federal Police (AFP) and the remaining four for the Australian Criminal Intelligence Commission (ACIC).

The ACLEI cautioned the increase in notifications didn't necessarily indicate a rise in actual corruption, attributing it instead to the department's "growing maturity".

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