1. You and your two brothers contribute $2,000 each toward the support of your mother. She contributes $1,000 of her own to support herself. Your two sisters contribute $500 each. Thus, the total support comes to $8,000. Of this, you and your brothers each gave 25% ($2,000 ÷ $8,000), for a total of 75%. Each sister gave 6¼% ($500 ÷ $8,000). You or one of your brothers may claim the exemption, assuming the other tests for a qualifying relative (21.4) are met. Since each of you contributed more than 10% and the total of your contributions is more than half of your mother’s support, you may decide among yourselves which of the three of you will claim the exemption. If you claim the exemption, your brothers must sign Forms 2120, which you attach to your return. If one of your brothers claims the exemption, you sign a Form 2120, which is attached to the return of the brother who claims the exemption. Since neither of your sisters furnished more than 10%, neither can claim the exemption; they need not sign Forms 2120.

2. Your mother’s support totals $10,000; you contribute $3,000; your brother, $2,000; your father, $1,600; and your mother from her savings contributes $3,400. Assume your father does not file a tax return claiming your mother as an exemption. You and your brother cannot use your father’s contribution to meet the more than 50% test required by Rule 2 above. Your father may not join in a multiple support agreement because your mother is not his dependent for tax purposes, although an exemption may be claimed for a wife on the basis of the marital relationship (21.2).