Reinvestment in primary residences under construction is of concern to many people, and more so at a time when a high percentage of the population wants to change their residence to buy houses in newly built urbanizations or neighbourhoods. In this sense, the Supreme Court, in a Judgment of February 17, 2021, has established doctrine, considering that, in cases in which the profits obtained from the sale of the habitual residence are destined to the acquisition of land to build the new habitual residence or in a new home under construction (regardless of its phase), taxpayers will have a period of two years to benefit from the tax exemption on the amounts reinvested, even when the declaration of completion of work is after said period. When we sell a home and obtain profits for it, personal income tax taxation may involve a cost of between 19% and 23%, depending on the amount of profit obtained: fixed rate of 19% up to 6,000 euros, 21% (from 6,000 to 50,000 euros) and 23% (from 50,000 euros onwards). So, in summary, with the reinvestment in the main residence, the tax savings are quite high . On the other hand, the exclusion of this tax applies only to the proportional part of the reinvested capital gain. Let's take a practical example: we have just sold our habitual residence, which cost us 90,000 euros, for 100,000 euros, generating a capital gain of 10,000 euros. With the money obtained, we decided to buy an apartment valued at 80,000 euros that will become our new habitual residence. In this case, we would be entitled to an exemption for reinvestment in the main residence of 80% of the capital gain, since this is the percentage that we are going to allocate to the new home. This means that, in the next Income Statement, of the 10,000 euros obtained from capital gains, 8,000 euros would be exempt from taxation and the other 2,000 euros would have a 19% tax.