Companies that want to tender for ACT government work will need to be audited to prove they have not ripped off their workers, if draft laws pass the ACT Legislative Assembly on Thursday.

The provisions would apply to any government work procured from the construction and cleaning industries from January 15, 2019. Other industries will follow.

Construction contractors tendering for ACT government work are already required to hold an Industrial Relations and Employment Certificate, which is similar to the incoming  Secure Local Jobs Certificate.

But Master Builders Association ACT executive director Michael Hopkins said two months was not long enough for small construction firms to jump through the required hoops, and called for a six-month extension.

"The problem is small businesses and government are not prepared for this. The government needs to appoint a registrar, they need to approve guidelines and forms. The registrar needs to appoint auditors and provide information and training to contractors. Then contractors need to engage the auditor and go apply for their certificate, for small businesses to be eligible for government work. In our view it's simply unworkable," Mr Hopkins said.

Mr Hopkins said small businesses would be left unable to tender for government work if the laws were "rushed through".

He was also concerned the government would have to hold back tenders to give businesses more time to become compliant.

"Around $600 million worth of construction work is tendered every year from the ACT government. Either small business is not going to be able to tender for work or ... if they held back tenders it would starve the industry of work," Mr Hopkins said.

However, a spokesman for Employment Minister Rachel Stephen-Smith said they would not change the timeframe.

"This legislation comes after significant time and consultation, including a committee inquiry and two rounds of formal consultation with the community," he said.

"There have also been a number of meetings with industry and employee representatives over many months to discuss matters in relation to the Secure Local Jobs Package."

The spokesman said while construction companies tendering for new work from January 15 will need to be code certified, "the bill does not require all current IRE certificate holders to be re-certified, as the MBA appears to be suggesting".

Employer groups have opposed the new code, which is a formalisation of a longstanding agreement between the Barr government's and Unions ACT, amid concerns it hands too much power to unions.