“Which, in the context of the shortage we are in, (we) obviously cannot allow,” he added.
The move was therefore designed to “prioritise affordable homes for residents”, he said.
Sánchez did not provide details on how the tax would work or a timeline for presenting it to parliament for approval, where he has often struggled to muster enough votes to pass legislation.
But his government said the proposal would be finalized “after careful study”.
It is one of a dozen planned measures announced by the prime minister on Monday with the aim of improving the affordability of housing in the country.
Other measures announced include tax relief for landlords providing affordable housing, the transfer of more than 3,000 homes to a new public housing authority, and stricter regulation and higher taxes on tourist accommodation.
“It is not fair that those who have three, four or five apartments for short-term rent pay less tax than hotels,” he said.
