National Australia Bank chief executive Andrew Thorburn has taken a $2.1 million pay cut.

He will still take home $4.3 million for the year to September 2018, but it is a serious reduction on the $6.4 million for the same period the year before.

It comes as bank chiefs including Mr Thorburn prepare to face an intense grilling at the royal commission’s final round of hearings on Monday.

The NAB board said Mr Thorburn had “performed strongly” in a difficult environment, but

factors including issues raised at the royal commission mean Mr Thorburn could not receive his full bonus.

“The group CEO has accepted accountability for NAB's failure to fix mistakes quickly, remediate customers promptly and set things right,” the bank’s remuneration report said.

“These failures have impacted NAB's reputation.”

Meanwhile, Mr Thorburn has been tied in to police investigations over bribery allegations.