No, registered domestic partners should not report social security benefits as community income for federal tax purposes.
For federal tax purposes, the treatment of social security benefits as community income is determined by state law. If state law does not classify social security benefits as community income, then they are not considered community income for federal tax purposes. This principle is consistent with the general rule that federal tax is determined based on state-created rights and interests in property. Therefore, unless state law specifically designates social security benefits as community income, registered domestic partners should not report them as such on their federal tax returns.
Sources:
Publication 555 (3/2020)
Rev. Rul. 2013-17
§ 61. Gross income defined
IRM Part 25. Special Topics. Chapter 18. Community Property. Section 1. Basic Principles of Community Property Law
IRM Part 25. Special Topics. Chapter 18. Community Property. Section 2. Income Reporting Considerations of Community Property
