Cheats are still getting away with it because contractors are not using the latest technology to carry out checks.
A UK-wide survey also found that while 86% of cardholders had their cards checked, under half (43%) were checked to see if they were actually qualified to do the job.
The survey, by the Construction Industry Training Board (CITB) and the Construction Skills Certification Scheme (CSCS) is part of a drive for construction firms to adopt new technology to identify fraudsters.
All 1.4 million CSCS cards have microchip technology embedded in them, which allows a site manager access to a wealth of information about each worker, including their qualifications.
But 69% of respondents said they were still checking cards using a paper-based system, with only 6% using smart technology.
Braden Connolly, Head of Product Management at CITB, said: “Producing or using cards fraudulently can constitute a criminal offence.
“Increased action is needed to stamp out the fraudsters, which is why we are calling on industry to adopt new technology to help tackle this problem.
“CITB will continue to share intelligence and work with the authorities whenever the evidence suggests criminal activity is taking place.”
CSCS Chief Executive Graham Wren said: “Thorough card checks must be carried out before allowing workers on site and employers need to ensure workers have the correct qualifications for the work they do.
“More and more people are realising technology, such as a CSCS SmartCard, is a simple and cost effective way to do this.
“By simply placing the card into a reader or compatible device such as a tablet or smartphone you can instantly check the validity of a card and the qualifications held by the card holder.
“There is still a lot of work to be done to increase the use of technology so that relying on visual card checks becomes a thing of the past.”
To read the full survey click here