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The basics
Married filing separately means each spouse files an individual return. In the model, income belongs to the person who receives it, and each return has its own brackets, deductions, and income tests.
Some rules are more restrictive than for a joint return, including rules for IRA contributions, Social Security, Marketplace credits, and Medicare surcharges. The guide below explains the assumptions the model applies.
Illustrative numbers
Why the split matters
Two equal $150,000 earnersthe same tax as filing jointly — the separate ladder is exactly half the joint one
One $300,000 earnerabout $18,700 a year more than filing jointly
$60,000 of Social Security, living togetherup to 85% taxable from the first dollar, against a joint return that shelters most of it
The answer depends on how evenly the income is split between the two of you, which is why the plan prices two real returns rather than one pooled figure.
Calculation transparency
How it works in MoneyWhatIf
- 01
Each person's streams, accounts, pre-tax deferrals and half of the self-employment tax land on their own return; property tax, mortgage interest and rental income follow the deed, half each where it is joint; declared giving and medical go where the declaration says, half each by default.
- 02
In the nine community-property states — Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington and Wisconsin — earned income, interest, dividends and rent are split evenly between the two returns; IRA and pension distributions and Social Security stay with the person paid. A couple who lived apart all year are not split.
- 03
The standard deduction is denied to either spouse when the other itemizes, so the pair is priced both ways and the cheaper kept.
- 04
Withdrawals, required minimums and scheduled distributions are charged on the account owner's return, so drawing from the lower-earning spouse's IRA is priced as the cheaper move it is.
- 05
A Roth conversion is charged on the converted account's owner's return and a gain harvest on the brokerage account's owner's; the extra interest and dividends on money swept into savings land on the swept account's owner's return, the cash reserve's own interest half each.
A property sale's gain and depreciation recapture follow the deed — half each where it is joint — with the $250,000 home-sale exclusion taken once on each return that sells a share, so two half-owners reach $500,000 between them and a home in one name reaches $250,000.
- 06
Medicare's surcharge is set per person on that person's own return two years back, on the three-tier separate table; the death of a spouse collapses the two returns onto one joint return for that year and the qualifying years after it, then single.
- 07
The state line is priced on each state's own separate-filer schedule: the single ladder in the 44 jurisdictions where that is the law (New Jersey and New York print the separate return on their single schedule), and the state's published married-filing-separately table in Maryland, Minnesota, North Dakota, New Mexico, Vermont, Wisconsin and West Virginia.
Where a state writes a separate column for a figure beside the ladder — Connecticut's $12,000 exemption and $2,500-step phase-out, the halved deduction limits of Maryland, Minnesota and New York, the halved property-tax ceilings of Oregon, Minnesota and New Jersey, and the Maine, New Mexico and Wisconsin retirement gates — that column is what the return reads.
Keep in mind
Model limits
Income-driven student loan repayment, the main reason to elect this status, is not modelled at all.
Separate property in community-property states cannot be tagged, so everything held is treated as community except retirement-account distributions and Social Security.
A capital-loss carryforward is one household pool, spread across the two returns in proportion to the sale gain each carries rather than kept per person.
No federal credit is priced for any status, so the credits filing separately shuts off are absent rather than denied; the $1,500 capital-loss limit is not modelled because the $3,000 one is not either.
The status is one answer for the whole plan; a real couple chooses again every year.
This explanation documents the planning model. It is educational, not individualized tax, legal, Medicare, or investment advice.
Where it appears
Where to use it
See this concept in context, with a guide to each page and its controls.
The words behind it
Related financial terms
Plain-English definitions, with 2026 figures and worked examples, from the financial terms glossary.