If you’re in a registered domestic partnership or civil union, the federal government treats you as single for tax purposes, and that single fact drives almost every way domestic partnership affects your taxes. You can’t file jointly, you don’t get the marital deduction on gifts or inheritances, you can’t make spousal IRA contributions, and you generally can’t collect Social Security based on your partner’s record. State rules sometimes go the other way, which creates its own paperwork. The gap between what a married couple pays and what two domestic partners with identical finances pay is real, and in some situations it’s substantial.
Federal Filing Status
The IRS does not recognize domestic partnerships or civil unions, regardless of what your state calls the relationship.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions Married Filing Jointly and Married Filing Separately are off the table. Each partner files their own Form 1040.
Your default status is Single. You may qualify for Head of Household if you pay more than half the cost of keeping up your home and a qualifying child or qualifying relative other than your partner lives with you for more than half the year.2Internal Revenue Service. Publication 501 (2025), Dependents, Standard Deduction, and Filing Information Your partner alone cannot be the person who qualifies you, even if you claim them as a dependent.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions
The distinction has bite. For 2026, the standard deduction is $16,100 for a single filer and $24,150 for Head of Household.3Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill A married couple filing jointly gets a larger combined deduction and access to wider brackets. Two partners with the same combined income as a married couple often end up paying more federal tax.
State Rules and Community Property
Some states that recognize domestic partnerships require or allow partners to file the state return using a married status. That leaves you single federally and married for state, and bridging the two usually means preparing a mock federal joint return just to compute the state number. It costs time and, if you use a preparer, money.
Community property states raise the stakes. In California, Nevada, and Washington, registered domestic partners are subject to community property rules, so most income earned by either partner during the relationship belongs equally to both. For federal purposes, each partner reports half of the combined community income on their own return. Publication 555 sets out the rules, and Form 8958 has to be attached to show the split.4Internal Revenue Service. Publication 555 (2024), Community Property Getting the allocation wrong is one of the more common audit triggers for registered domestic partners in these states.
Claiming Your Partner as a Dependent
You may be able to claim your partner as a “qualifying relative.” Every one of these tests must be met at the same time: your partner’s gross income for the year is under $5,050; you provide more than half of their total support; they live with you all year as a member of your household; they are a U.S. citizen, U.S. national, or resident of the U.S., Canada, or Mexico; and no one else can claim them as a qualifying child.5Internal Revenue Service. Dependents The income test is what usually rules it out. A partner earning even modest wages exceeds the threshold.
If your partner does qualify, you can claim the Credit for Other Dependents, a nonrefundable credit worth up to $500.6Internal Revenue Service. Understanding the Credit for Other Dependents A partner’s child may also qualify as your dependent under either the qualifying child or qualifying relative rules, and when both partners share a household with one partner’s child, deciding who claims the child can move each return meaningfully.
Employer Health Coverage and Imputed Income
Many employers extend health insurance to domestic partners. Because the IRS doesn’t treat your partner as a spouse, the coverage doesn’t get spouse-level tax treatment. The exclusion for employer contributions to accident and health plans generally covers the employee and their legal spouse or tax dependents.7Office of the Law Revision Counsel. 26 U.S. Code 106 – Contributions by Employer to Accident and Health Plans
When your employer covers your partner, the fair market value of that coverage is added to your taxable wages as imputed income. It appears on your W-2 and is subject to federal income tax, Social Security tax, and Medicare tax. If your partner’s coverage costs the employer $6,000 a year, you’re taxed on an extra $6,000 you never see. A married employee with identical coverage for a spouse pays nothing extra.
There is one exception. If your partner qualifies as your tax dependent under the tests above, the coverage can be excluded from your income.1Internal Revenue Service. Answers to Frequently Asked Questions for Registered Domestic Partners and Individuals in Civil Unions The gross income limit makes that hard to reach for partners with meaningful earnings.
Gifts and Estate Transfers
Spouses can transfer unlimited assets to each other during life or at death without gift or estate tax. That marital deduction is available only to legal spouses.8Office of the Law Revision Counsel. 26 USC 2056 – Bequests, Etc., to Surviving Spouse Domestic partners get none of it.
For 2026, you can give your partner up to $19,000 in a year without filing a gift tax return. Anything above that counts against your lifetime exemption of $15,000,000.3Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill Most people won’t owe gift tax because the lifetime exemption is high, but you still have to file Form 709 for any gift over the annual exclusion, and every dollar transferred between partners chips at that lifetime limit.9Internal Revenue Service. What’s New – Estate and Gift Tax
Estate consequences hit harder. When one partner dies and leaves assets to the surviving partner, the full value is included in the decedent’s taxable estate. A spouse would inherit the same assets tax-free. For partners with combined assets approaching the lifetime exemption, that can mean hundreds of thousands in estate tax that a married couple would never owe. Estate planning counsel isn’t optional at that scale.
Everyday planning moves have the same edge to them. Adding your partner to your home’s title by quitclaim deed is a taxable gift of half the fair market value. On a $500,000 home, that’s a $250,000 gift, well over the annual exclusion, and it triggers a Form 709.
Retirement Accounts
No Spousal IRA
In a marriage, a working spouse can fund an IRA for a non-working spouse through a spousal IRA. For 2026, that’s up to $7,500 per person, or $8,600 at age 50 or older.10Internal Revenue Service. 401(k) Limit Increases to $24,500 for 2026; IRA Limit Increases to $7,500 The spousal IRA requires a joint return. If your partner isn’t working, you can’t contribute to an IRA on their behalf. They need their own earned income.
Inherited IRAs and 401(k)s
A surviving spouse who inherits an IRA or 401(k) can roll it into their own account and take distributions on their own timeline. A domestic partner inherits as a non-spouse. Unless they qualify as an eligible designated beneficiary (which requires being disabled, chronically ill, or no more than 10 years younger than the deceased), the entire account has to be emptied within 10 years of the account holder’s death.11Internal Revenue Service. Retirement Topics – Beneficiary
The 10-year window can produce a large tax bill. A $500,000 traditional IRA left to a partner has to come out over ten years, and every dollar comes out as ordinary income. Spreading the same account over a surviving spouse’s lifetime produces far lower annual tax. It’s one of the biggest hidden costs of partnership compared to marriage.
Splitting Shared Income and Deductions
Mortgage Interest and Property Taxes
If you and your partner co-own a home, each of you deducts the portion of mortgage interest and property taxes you actually paid. When both partners are on the loan and pay from a joint account with equal contributions, a 50/50 split is standard.12Internal Revenue Service. Other Deduction Questions 2
Only one partner receives the Form 1098. That partner claims their share on Schedule A, line 8a. The other partner claims their share on line 8b and, on a paper return, attaches a statement identifying the partner who received the 1098 and explaining the split.13Internal Revenue Service. Publication 936 (2025), Home Mortgage Interest Deduction Keep records of who paid what. The deduction only holds up if you can back it up.
Joint Bank Interest
Shared bank accounts earn shared interest, but the bank issues a single Form 1099-INT, usually in the primary holder’s name. Married spouses can just report it. Domestic partners can’t. The partner who received the 1099-INT is treated as a nominee for the other partner’s share and has to file a separate 1099-INT with the IRS allocating the correct portion, then furnish a copy to the partner.14Internal Revenue Service. Topic No. 403, Interest Received Skip that step and the IRS assumes all the interest belongs to the name on the form.
Charitable Gifts and Medical Expenses
You can only deduct what you personally paid with your own funds. If your partner writes the check to charity from their account, the deduction is theirs. Record-keeping during the year does the work; you can’t reconstruct it in April.
Social Security
Social Security is built around marriage. A legal spouse can claim spousal benefits on their partner’s record and survivor benefits after their partner’s death. Domestic partners generally do not qualify for either. The Social Security Administration has recognized limited exceptions for some same-sex couples in civil unions or domestic partnerships under specific circumstances, but those exceptions are narrow and fact-dependent. For most domestic partners, each partner’s benefits track their own earnings history, with no claim on the other’s record.
Where one partner earned much more over a career, the gap can mean tens of thousands in lifetime benefits that a surviving spouse would have collected automatically.