THERE was a time when you couldn't lay your hands on an overbooked tradesman to convert your SSIA into a new kitchen.

Today, however, a new generation of rogue traders desperately competing for work and operating 'off the books' is costing the exchequer as much as €350m a year in unpaid tax.

With the construction industry on its knees, the building lobby has met with the Revenue Commissioners to discuss the rise in blackmarket builders.

According to the Construction Industry Federation (CIF) as much as 10% of current industry turnover is restricted to the 'shadow economy'.

Turnover for 2011, it said, would amount to around €10bn compared to €38bn at the height of the building boom. Around €1bn of that is likely to be under the table, translating to lost tax revenue in an economy where every euro is sacred.

"The blackmarket was always in existence but it does grow whenever there is a recession," said CIF director Don O'Sullivan.

A lot of the activity is thought to be centred on the one-off housing industry.

"There is concern that a lot of the labour used in these self-builds are in the shadow economy and they are not declared," said O'Sullivan.

The CIF has called for mandatory site notices on one-off projects detailing contractors involved, and jobs worth in excess of €3,000 to be notified to the Revenue.