KINSHIP WITH THE DECEASED

A non-married partner is classified as a non-related beneficiary, as are the children of the non-married partner.
There are a lot of special rules in each Comunidad Autonoma related to this issue, if applicable. These are mainly in order to assimilate married and non-married couples, and depend on whether that union has been constituted according to the rules of each individual Comunidad Autónoma and included in its register of non married couples.

A link by adoption is considered to be equal to that of a link by blood .

A separated married couple is consider a widow or widower if no divorce has been settled.

Parentesco por afinidad ( Kinship in-law) is the kinship that links a person with the blood relations of the married partner
A descendant or an ascendant- in- law ( father or mother ; son or daugther-in- law) as well as a stepchild is included in the inheritance tax law as kin in Group III.

The colateral blood relations are not included in the law but recent court Judgements state that if the law does not distinguish, we must not distinguish either, so brothers, uncles, aunts, nephews and nieces by marriage are also in Group III, as are the corresponding blood relations, but only during the marriage.

If a person is only related to the deceased through a blood link to the previously dead or divorced spouse, that person is now considered as non related.