The only house no longer used as a main residence, how should it be indicated on 730?

For tax purposes, a principal residence is considered to be the one in which the taxpayer or his family members (spouse, relatives within the third degree and relatives by marriage within the second degree) habitually reside. For the property, the deduction from the total income is due up to the amount of the cadastral income of the house and its appurtenances, calculated taking into account the share of ownership and the period of the year in which the house was used as a main residence.