Depends on the tax rules that apply to the country you are claiming in.
"Claiming" is the present participle of "claim".
was/were claiming
You can claim nationality through birthright (being born in a specific country), descent (having parents who are nationals of a country), marriage to a national, or through the process of naturalization (applying for and obtaining citizenship in a specific country). Each country has its own laws and requirements for claiming nationality.
France was the first European country to explore and claim lowa, with French explorer René-Robert Cavelier, Sieur de La Salle, claiming the area for France in the late 17th century.
This is not a crime, according to Jewish law. Furthermore, no one in Jewish history has every made this claim seriously (not counting the original kings of Israel: Saul, David, and Solomon).
The verb to claim has the participles claimed and claiming. Claimed is more often used as an adjective.
It depends on how they make that claim. Bedouin and Druze claim that Israel belongs to them as much as it belongs to the Jews and proudly call themselves Bedouin Israelis and Druze Israelis. A number of Arabs who formerly lived in what is now Israel or the Occupied Territories claim that the Jewish State is illegitimate and demand that country be returned to them for administration. These individuals are called Palestinians. (Admittedly, a number of Palestinians are willing to allow Israel to exist outside of the Occupied Territories, but there is no difference in naming between the Two-Staters and the One-Staters.)
Both claim the entire Southwest Levant, termed by the Jews as "Eretz Yisrael - The Land of Israel" and by the Arabs as "Belaad Filastin - The Country of Palestine", as their homeland.
If you are a citizen of British Columbia then no, it's not illegal to claim single.
You need to include what they are claiming for and from whom.
If you are filing as married and the child's other parent does not claim them, or is disallowed from claiming them.