A troubled overhaul of a payroll and human resources system for police has been given a "red" rating by Treasury - amid concern a budget blowout will worsen.

The whole-of-life budget for the new Human Resources Management Information System has increased by about $8 million and will now be up to $64 million.

Police pushed the go-live date out to next Monday, but this month announced a further delay to April next year.

The Treasury is monitoring the system as part of its work overseeing the Government's 55 riskiest projects, which total $36 billion.


Read the full report here.

The projects span 33 agencies and are assessed using a five-point scale ranging from red to amber and green.

The police payroll system has now worsened from amber/red to red.

"The project is in the testing phase and given its complexity it is not surprising that testing has identified defects, though the number and severity of these has significantly exceeded expected levels and has put pressure on the schedule and budget," Treasury commented.

"Police are continuing commercial conversations following vendor performance issues and project delays. There is ongoing risk that further major defects add to delays and costs."

It was better news for the Ministry of Health's plans for a national bowel screening programme, which improved from a red rating to amber/red.

However, Treasury fears the rollout schedule "still appears extremely difficult to achieve".

This year's Budget set aside $39.3 million over four years to implement the national programme.

The investment built on the successful Waitemata District Health Board's bowel screening pilot, which has been running since 2012. Once the programme is in place, DHBs will offer people aged 60 to 74 a bowel screening test every two years.

Another major health project to cut DHB data centres from 40 to two IBM-managed centres has been delayed from its earlier start date in July, and is a new entrant in the Treasury report at an amber/red rating.

Finance Minister Bill English said 84 per cent of projects in the previous assessments were amber or better, and that was now 92 per cent. He said it was not unexpected for some projects to be given a lower rating.

"The purpose of the report is to highlight which projects may be facing challenges and need extra support."