Paying cash in hand to visiting builders is a threat to reputable Isle of Man firms according to the President of the Employers Federation.
Les Nicol says it also puts any local sub-contractors used at risk of not being paid.
The subject of the so-called "black economy" within the construction industry, and protecting the interests of sub-contractors, was raised at question time in the House of Keys on Tuesday.
Les Nicol says he believes companies based here act lawfully and is urging people not to employ cowboy builders
House of Keys officially dissolved
Students collecting A-Level results
Further TT course closures for filming
Aspects of Manx Grand Prix 'extremely challenging' to organise