The Ministry of Finance is looking at ways of forcing companies such as Airbnb and Portugal's 'Uniplaces.' to report property owner data.
The objective is to catch those owners who are involved in tax fraud and tax evasion.
Property owners pay commissions to do business on these booking platforms and later report their income to Finanças. Those turning over more than €10,000 annually, must register for and charge VAT, albeit at a reduced rate of 6%.
The president of the Local Accommodation Association (ALEP) confirms that Finanças has been intensifying its persecution of the local property rental (Alojamento Local) sector.
Eduardo Miranda argues that the tax authorities, "have already been crossing information about owners of local accommodation."
"Compelling foreign companies to give information about their clients in Portugal does not seem to me to be the most viable and practical way to have access to more data," says Miranda.
"I do not even know if the question of the privacy of customer data has been raised," said the accommodation association president, noting his members have, "made a leap in legalisation and compliance with tax obligations."
Local Accommodation tax revenue reached €123 million in 2017, doubling in more than a year, according to the latest available data on tax revenues from this sector.
The increase was due to the new regulation for the sector, approved in 2014, which led to the legalisation of many rental properties that had been operating under the radar.
The tourist boom saw over25,000 new registrations, a record amount, according to Turismo de Portugal.
Many owners turn to booking platforms such as Airbnb to get their customers and currently there are 83,177 registered properties, according to Turismo de Portugal.