In California, registered domestic partners do not file taxes together on their federal return but generally do file together on their state return. The IRS treats each partner as unmarried, so each files a federal return as Single (or Head of Household if separately qualified). California, by contrast, requires partners to use a married filing status on the state return, which means most file jointly. The result is two sets of returns prepared under two different rulebooks, tied together by California’s community property law.
Federal Returns Use Single Status
The IRS does not recognize registered domestic partnerships as marriages. You cannot file a joint federal return with your partner, and you cannot use Married Filing Separately either. Your only options are Single or, if you independently qualify, Head of Household.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions
Head of Household carries a larger standard deduction and better brackets than Single, but your partner does not count as a qualifying person for that status, even if your partner is your dependent. You need a qualifying child or other qualifying relative who is not your partner.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions
Because you file as Single, each partner uses the Single standard deduction and narrower brackets. Married couples filing jointly effectively double many of those thresholds. Domestic partners don’t get that federal benefit, so the combined tax bill on the same household income can be higher than a married couple would pay.
California Returns Use a Married Filing Status
California treats registered domestic partners identically to married couples for state income tax purposes. Since tax year 2007, you must file your California return using Married/RDP Filing Jointly or Married/RDP Filing Separately. Head of Household and Qualifying Surviving Spouse are also available if you meet the criteria.2Franchise Tax Board. Registered Domestic Partner (RDP) Filing Status
Most partners file jointly at the state level because it usually produces a lower combined state bill. If you file separately in California, community property rules still apply: each partner reports half of all community income plus all of their own separate income.3Franchise Tax Board. Married/RDP Filing Separately
Reconciling Two Different Returns
Your federal filing status is Single but your California status is Married/RDP, so the numbers on the two returns won’t line up. The Franchise Tax Board tells you to combine income and deductions from both partners’ federal returns to complete the California return, and to check the box indicating the California status differs from the federal status.2Franchise Tax Board. Registered Domestic Partner (RDP) Filing Status
A common workaround is to prepare a “pro forma” federal return. You fill out a Form 1040 as if the two of you were married filing jointly, use those figures to calculate the AGI and deduction numbers the California return needs, and keep the pro forma return in your files. It never goes to the IRS.4Franchise Tax Board. FTB Publication 737 – Tax Information for Registered Domestic Partners
Community Property Splits Income on Both Returns
California is a community property state. Almost everything earned during the partnership belongs equally to both partners: wages, salaries, business income, and earnings from community assets. Property owned before the partnership, along with gifts and inheritances received at any time, stays separate and is reported only by the partner who owns it.5California Legislative Information. California Family Code 760 – Community Property
The split applies on the federal return too. Even though you file as Single, each partner must report half of all combined community income and deductions. If one partner earns $120,000 and the other earns nothing, each reports $60,000 on their federal return.6Internal Revenue Service. Publication 555 – Community Property
Form 8958 Shows the Allocation
To show the IRS how community income was divided, attach Form 8958 (Allocation of Tax Amounts Between Certain Individuals in Community Property States) to each partner’s federal return. The form covers wages, self-employment income, interest, dividends, rental income, and taxes withheld, listing each item’s total alongside each partner’s allocated share.7Internal Revenue Service. About Form 8958, Allocation of Tax Amounts Between Certain Individuals in Community Property States
Both partners need to be able to identify which income and deductions are community and which are separate. Clear records throughout the year make this much easier, especially where one partner has separate investments or brought assets into the partnership.8Internal Revenue Service. Form 8958, Allocation of Tax Amounts Between Certain Individuals in Community Property States
Self-Employment Tax Works Differently Than It Does for Married Couples
Here the RDP rules diverge from marriage in a way that can cost real money. When married couples file separately in a community property state, the spouse who actually runs the business pays all the self-employment tax, even though each spouse reports half the business income. That provision does not apply to registered domestic partners.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions
Each RDP files their own Schedule C reporting half the business income and deductions, and each owes self-employment tax on their half of the net earnings. If one partner runs a business netting $150,000, both partners pay self-employment tax on $75,000. The total SE tax is unchanged, but the non-working partner now has a self-employment tax obligation on income they didn’t earn, which can trigger estimated tax payment requirements.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions
Claiming Children and Dependents
If both partners are legal parents of a child who qualifies as a dependent, either parent can claim the child, but not both. When both claim the same child, the IRS awards the dependency to the parent the child lived with longer during the year. If the child spent equal time with each parent, the partner with the higher AGI gets the claim.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions
Coordinating who claims the child matters. The partner who claims the dependency gets access to the Child Tax Credit, potentially the Earned Income Tax Credit, and may qualify for Head of Household. Since RDPs already face a structural disadvantage by filing as Single, placing the dependency claim with the partner who benefits most helps offset some of that gap.
Health Insurance Can Create Imputed Income
When an employer covers a married employee’s spouse under a health plan, the coverage is tax-free. When the same employer covers an employee’s domestic partner, the federal government treats the employer’s contribution as taxable income to the employee unless the partner qualifies as a tax dependent under IRS rules. The fair market value of the partner’s coverage appears on the employee’s W-2 as imputed income and increases both income tax and FICA obligations.9State Controller’s Office. Domestic Partnership FAQs
If your partner qualifies as your tax dependent, imputed income does not apply and the coverage is tax-free, just like spousal coverage. The dependent test follows the standard IRS rules for qualifying relatives, including income limits and the requirement that you provide more than half of your partner’s financial support. A partner with significant income of their own probably won’t meet the threshold.
No Community Income Relief for RDPs
Married couples who file separately have a safety net. If one spouse hides community income, the other can seek relief from the tax liability, provided they didn’t know about it and it would be unfair to hold them responsible. That relief does not extend to registered domestic partners. The IRS has stated the community income relief provisions do not apply to RDPs.10Internal Revenue Service. Publication 555, Community Property
If your partner earns community income and doesn’t report it, you may still owe tax on your half with no path to relief. Share complete financial information with each other and coordinate returns carefully every year. When the relationship is strained, the risk grows.
Practical Tips for Filing
The biggest mistake RDPs make is treating their taxes like two independent single returns. Even though the IRS considers you unmarried, community property rules tie your returns together. If one partner’s numbers don’t match the other’s community income allocation, the IRS can flag the inconsistency.
- Prepare both federal returns at the same time so the community income split on each Form 8958 is consistent.
- Track separate property carefully. Income from assets owned before the partnership, or from gifts and inheritances, does not get split. Keeping separate property in separate accounts avoids commingling problems.
- Some tax professionals start with the California joint return and work backward to the federal returns, because the state return is often simpler.
- Budget for the complexity. These returns take more work than a standard married filing jointly return, and preparer fees usually reflect the extra forms and reconciliation.