The core mechanism is simple: a state extends residency rights to non-citizens who invest a qualifying amount in housing. The minimum investment differs greatly between countries, novigrad real estate and governments change it regularly.
One key point divides residence and naturalisation. A residence permit lets you live there, usually on a renewable basis, while a passport normally requires a long period of residence. Any offer of a passport in return for an apartment purchase is reason for caution.
Beyond the purchase price, such permits impose additional requirements. Typical examples involve a clean criminal record, private health insurance, evidence of sufficient means and a minimum number of days in the country each year. Overlooking one of these can end the residency even if the property is still yours.
Fiscal residency forms an entirely separate matter. Owning property does not automatically make you a tax resident, and crossing the day-count threshold frequently does. Many countries use a threshold based on days spent locally, and the consequences reach earnings from abroad.
A sensible approach is essentially simple: buy something you would be happy to own, and latchi rentals let the permit be the second reason. These routes get restructured with limited notice, and a property chosen only for a permit proves difficult to let and difficult to sell.