The Government's spending watchdog will assess the "effectiveness and efficiency" of the gun buyback scheme and whether it meets its objectives.
The Auditor-General today announced it would report back to Parliament early next year after it had looked at how well the scheme was implemented, given its "significant public interest".
The safety and ease of the process for people attending the gun collection events will come under the microscope, as will whether or not the cost of the buyback scheme has been accurately accounted for.
In this year's Budget, more than $200 million was allocated to fund the buyback scheme, which will run until December 20 this year.
The Auditor-General will also look into how well the risks associated with the scheme were managed and the accuracy of the police's reporting on the scheme.
After the March 15 shootings which claimed the lives of 51 people in two mosques in Christchurch, the Government moved swiftly to ban most semi-automatic assault rifles as well as certain high-capacity magazines.
In a statement, the Auditor-General said it wanted to provide useful insights to New Zealand Police as the work was being carried out.
"Therefore, we are providing police with real-time assurance from our appointed auditor."
The police would be provided with regular reports on the effectiveness of elements of the buyback, such as collection processes and events.
"We will use the results of the appointed auditor's assurance work to inform our reporting to Parliament. We expect to report on the buyback scheme in February 2020."
At the halfway point of the gun amnesty, more than 12,000 people have handed in close to 20,000 firearms and 74,000 parts, and $36.7 million has been paid out.
Speaking to MPs at a select committee last week, Deputy Commissioner Mike Clement cited estimated the number of now-banned firearms was between 56,000 and 173,000.
But a report by KPMG, commissioned by the Government, revealed officials have no idea how many guns are in New Zealand.
This could push the cost of the buyback way up, according to the report.