As of Friday, all construction workers will be required to display their tax identification cards with an allotted tax number.
The tax cards are already compulsory gear on sites which began building works after last autumn.
Occupational health and safety officials, tax authorities and police will be conducting a coordinated program of spot checks to ensure that the new tax card regulation is being enforced in the sector. Employers and contractors who do not comply with the new regulation will be fined.
Finland introduced the tax number system to combat the rise of undocumented workers in the construction sector.