Whangarei MP Phil Heatley is to return to the Cabinet on Thursday, little more than a month after resigning in February over the misuse of his ministerial credit card.
Prime Minister John Key is reinstating Mr Heatley as Housing and Fisheries Minister, after the Auditor-General found he did not deliberately break spending rules.
Auditor-General Lyn Provost's report, which was released on Tuesday, says Mr Heatley did not understand the rules, and did not break them deliberately.
The report found Mr Heatley generally took care to account for his spending properly.
Mr Key says the rules were very confusing and while Mr Heatley made mistakes, he would be surprised if he was the first minister to do so. He says Mr Heatley is only human, and there is no reason to exclude him from the Cabinet.
"We've all in life made the odd mistake. If there's no deliberate pattern of behaviour, if there was no deliberate attempt to rort the taxpayer, and they are the findings of this report, then I can't see why he wouldn't be given a second chance."
Mr Key says Mr Heatley has proven to be a very good minister, and he believes he will be very careful in future.
He says Mr Heatley had done the right thing by resigning.
Expenditure reasonable - report
The report says Mr Heatley's overall ministerial office expenditure was reasonable compared with others, but a total of $1402 was outside ministerial and parliamentary rules.
It says Mr Heatley thought that in all cases the spending had been within the rules, but he did not understand them correctly.
The Auditor General accepted that Mr Heatley and his office did not break the rules deliberately.
However, the report says a more conservative approach that took greater account of how others might perceive his use of public money would have served him better.
Mr Heatley says he is grateful to have a second chance, but the rules around ministers' expenditure need to be clearer.
He says the Auditor-General also made it clear she thinks the rules need to be clearer.
"I'm pleased with the findings, because it shows my mistakes were unintentional, which is what I always said. Now that's been confirmed with a very thorough report and review, and now I want to get back on my horse."