Can a registered domestic partner be a dependent of his or her partner for purposes of the dependency deduction under section 151

Yes, a registered domestic partner can be a dependent of his or her partner for purposes of the dependency deduction under section 151, provided that the requirements of sections 151 and 152 are met.

To qualify as a dependent under section 151, the individual must meet the criteria of either a "qualifying child" or a "qualifying relative" as defined in section 152. Since a registered domestic partner is unlikely to meet the criteria for a "qualifying child," the focus will be on the "qualifying relative" criteria under section 152(d).

For a registered domestic partner to be considered a "qualifying relative," the following conditions must be satisfied:

1. Relationship: The individual must bear a relationship to the taxpayer as described in section 152(d)(2). A registered domestic partner can meet this requirement if they have the same principal place of abode as the taxpayer and are a member of the taxpayer’s household for the entire taxable year (section 152(d)(2)(H)).
2. Gross Income: The individual's gross income for the calendar year must be less than the exemption amount (section 152(d)(1)(B)). The exemption amount is subject to annual adjustments, and for the year 2013, it was $3,900. Given that registered domestic partners each report half the combined community income earned by both partners, it is unlikely that a registered domestic partner will have gross income that is less than the exemption amount.
3. Support: The taxpayer must provide over one-half of the individual's support for the calendar year (section 152(d)(1)(C)). If a registered domestic partner’s support comes entirely from community funds, that partner is considered to have provided half of his or her own support and cannot be claimed as a dependent by another. However, if the other registered domestic partner pays more than half of the support of the partner by contributing separate funds, the partner may be a dependent for purposes of section 151, provided the other requirements are satisfied.
4. Not a Qualifying Child: The individual must not be a qualifying child of the taxpayer or any other taxpayer for the taxable year (section 152(d)(1)(D)).

In summary, while it is possible for a registered domestic partner to be claimed as a dependent under section 151, it is challenging due to the gross income and support requirements. The registered domestic partner must have gross income below the exemption amount and must receive more than half of their support from the taxpayer's separate funds.

Sources:
§ 152. Dependent defined
Rev. Rul. 2003-58
Publication 555 (3/2020)