Construction, Forestry, Mining and Energy Union ACT secretary Dean Hall has expressed outrage that of the 12 new ACT WorkSafe inspectors promised in the ACT budget last month, only seven will be funded by September with the other five not brought on until next March.

A proposed new penalty system for shoddy builders through ''active certification'' has also been watered down until next year after successful lobbying by the Master Builder's Association that business needed more time to adapt to the system.

ACT Work Safety Commissioner Mark McCabe confirmed on Wednesday he had been informed that the $5.7 million ACT government commitment to 12 new safety inspectors would not be rolled out immediately, but staged over the next nine months.

The ACT government agreed in November of last year that the 12 new inspectors would be brought on as a matter of urgency with the independent ''Getting Them Home Safely'' inquiry recommending beefing up the inspectorate as a fundamental way to improve construction safety and compliance.

WorkSafe has a staff of 34.

Mr McCabe refused to criticise the government over the two-staged rollout, saying: ''We would always have had difficulty finding 12 new inspectors with the requisite skills and competence all at once.''

ACT Workplace Safety Minister Simon Corbell said the 12 new inspectors would be in place during the new financial year and that the ''staged implementation of the new inspectors recognises the time it will take to recruit and train suitable candidates for the positions.''

But Mr Hall said increasing reach and visibility had been a central recommendation of the inquiry and it was unacceptable that ACT families had to wait until March for the full rollout. ''Let's not forget four people died in quick succession last year because the ACT has the worst fatality rate in the country and a serious injury rate 33 per cent higher than the national average,'' he said.

In a bid to crack down on unscrupulous builders, the ACT government has committed to the introduction of active certification - in which companies are allocated a certain number of points much like a driver's licence and any safety breaches lead to points being lost and the potential for a company to be struck of the list of approved tenderers.

While the system was supposed to be introduced in full by July 1, the penalty system will not be introduced until January next year.

Mr Hall said the ''soft introduction'' was ''bowing to the interests of the MBA and is not in the interests of any families who have a member working in construction and who are statistically at risk of a serious injury or not even coming home at all''.

''Of course we are very concerned to see any sort of backsliding at all on these commitments to improve safety in construction,'' he said.

''What we have here are bean-counters and bureaucrats starting to interfere, to push deadlines back and to water down recommendations.''

Mr McCabe said an enormous amount of work had gone into developing the active certification system which he said would be a ''game changer''. ''It is important that we get this system right,'' he said.