Property owners who have added a pool or made other significant alterations to their property, without reporting it to the Finanças, could now face a huge increase in property tax (IMI). Many property owners will be having their home revalued under the new IMI rules and others are planning to sell; either of these cases will highlight any alteration to the property not previously reported. In such cases, the Finanças might charge property owners retrospectively for the previous four years. As part of the property revaluation process, around 5.4 million properties will be revalued by the end of the year.