At the moment, firms can dodge payment by simply not telling the board of their existence.
But last week, education and employment minister George Mudie gave a strong indication that the government was prepared to change the rules.
Mudie told a House of Commons Committee considering the CITB's latest levy proposals that he was willing to consider the board's proposal for mandatory registration.
Mudie said he would consider full details of the resources required, and the expected benefits and bureaucratic requirements, adding that he was unlikely to introduce mandatory registration before the CITB's next review.
Mudie's comments brought a cheer from the Construction Confederation.
The House of Commons and the House of Lords last week approved the CITB's latest levy proposals, which will see a levy of 0.38% of payroll for directly employed workers and 2.28% for labour-only subcontractors.
