How to File Married Jointly: Joint vs. Separate Returns for High-Income Parents in California and Washington

By Kevin Luu, Co-Founder and Chief Learning Officer. Reviewed on 2026-09-30.

For most married couples earning $750,000 to $3 million in California or Washington, filing jointly is the best way to file. Separate returns almost never lower federal tax at this income, because in both states wages earned during the marriage are community income that gets split 50/50 on separate returns, and the federal separate-return brackets are exactly half the joint ones. The one exception worth running the numbers on: California couples with more than $1 million of taxable income, where separate returns can lower state tax by up to $10,000 a year.

Below is how the math works, a worked example for a $1.6 million household with two kids, what separate returns cost you, and the steps to file a joint return correctly when one or both of you has RSUs.

Why joint and separate returns usually come out even at $1 million or more

Three rules do most of the work for a high-income couple.

• The brackets are mirror images. For 2026, the 37% federal bracket starts at $768,700 of taxable income on a joint return and at $384,350 on a separate return, exactly half (IRS Rev. Proc. 2025-32). The joint standard deduction is $32,200; each separate filer gets $16,100.
• California and Washington are community property states. If you file separately, each spouse reports half of all community income plus their own separate income (IRS Publication 555). Salaries and RSUs earned during the marriage are generally community income, so even a couple with very unequal paychecks ends up with roughly equal incomes on separate returns. That removes the usual reason to file separately, which is keeping one spouse’s income out of the other’s brackets.
• Most income-based limits are already gone. The Child Tax Credit is $2,200 per child for 2026, but it phases out completely for a joint filer with two children at a modified AGI of $488,000. The 2026 SALT cap of $40,400 shrinks to its $10,000 floor once joint MAGI passes about $606,333; on separate returns each spouse’s cap floors at $5,000, the same $10,000 in total.

So for a dual-W-2 household in San Jose or Bellevue, the choice is not about the federal bracket math. It is about California’s surtax on millionaires, legal liability, and paperwork.

Worked example: a $1.6 million Bay Area household, joint vs. separate

Assumptions (illustrative): Priya earns $1.1 million at a large tech company, about $600,000 of it from RSU vests. Daniel is a physician earning $500,000. They live in California, have two children aged 4 and 7, and all of their wages are community income. Each defers $24,500 to a 401(k), the 2026 limit, so federal AGI is $1,551,000. With the SALT deduction capped at $10,000 at their income, they take the standard deduction. For California, we assume taxable income of $1,500,000 on a joint return ($750,000 each on separate returns), and we use 2025 California rates because the 2026 schedules are not yet published.

Federal tax is identical to the cent. The whole difference is California’s 1% Behavioral Health Services Tax, which applies to taxable income over $1,000,000 on any return, joint or single (FTB Form 540 instructions, line 62). A joint return gets one $1 million threshold; two separate returns get two. The most a couple can save this way is $10,000 a year, reached once joint taxable income is $2 million or more.

California also requires you to use the same filing status as your federal return in most cases, so separating for California means separating federally too (same FTB booklet). In this example that costs nothing federally. Whether $5,000 is worth it depends on the costs below.

What filing separately costs a high-income couple

IRS Publication 501 lists the special rules for separate returns (Pub 501). The ones that matter at this income:

• Both spouses itemize or neither does. If one spouse itemizes, the other cannot take the standard deduction.
• The child and dependent care credit is lost in most cases. At this income the credit is small anyway; the dependent care FSA is the bigger lever. For 2026 it is $7,500 per household, or $3,750 for each spouse filing separately, so the total does not change.
• Capital loss deductions are halved. Each spouse can deduct $1,500 of net capital loss against ordinary income instead of $3,000 jointly.
• Rental losses. Spouses who lived together at any time in the year and file separately cannot use the special allowance for rental real estate losses.
• Paperwork. In community property states, each separate return needs Form 8958 showing how community income and deductions were split. RSUs granted before the marriage, or equity earned while living in another state, may be partly separate property, and someone has to document the split.

There is one non-tax reason to file separately. On a joint return, both spouses are responsible for the full tax, and the IRS can collect all of it from either one, even if all the income was earned by the other (Pub 501). If one spouse has a complex side business, an old tax dispute, or the marriage is under strain, separate returns limit that exposure. Innocent spouse relief exists for joint filers, but it is a claim you make after the fact, not a shield (IRS Publication 971).

Washington: no state reason to file separately in 2026, but watch 2028

Washington has no individual income tax on wages in 2026 (WA Department of Revenue), so for a Seattle or Redmond couple the filing decision is purely federal, and the community property split usually makes separate returns a wash. Washington’s 7% capital gains tax (9.9% on gains above $1 million) is filed with its own state return and is not a reason to change your federal status.

That changes in 2028. Washington enacted a 9.9% income tax on individuals and joint filers with AGI over $1,000,000, effective January 1, 2028, with first returns due in April 2029. DOR has not yet published how married couples filing separately will be treated. A Washington household well above $1 million should revisit filing status once that guidance is out.

Why the “average refund” is the wrong benchmark for RSU households

Many couples judge their filing status by the refund. At this income, the refund mostly measures withholding, and withholding on equity pay usually runs short.

Employers can withhold federal tax on RSU vests and bonuses at a flat 22% until supplemental wages pass $1,000,000 in a calendar year; above that, 37% is mandatory (IRS Publication 15). In the example, Priya’s $600,000 of RSUs is withheld at 22% while the couple’s top bracket is 37%. That is a gap of about $90,000 in federal tax that shows up in April, not a refund.

A second, smaller gap: each employer withholds the 0.9% Additional Medicare Tax only on wages it pays over $200,000, while a joint return owes it on combined wages over $250,000. With $1.6 million of combined wages, Priya’s employer withholds $8,100 and Daniel’s $2,700, but the joint return owes $12,150. The fix for both is the same: estimated payments or extra W-4 withholding, set once in the spring after the vesting schedule is known.

How to file a joint return: the steps that matter for an RSU household

1. Confirm you qualify. You can file jointly for 2026 if you are married on December 31, 2026, and both agree to file together. Both spouses sign. State law decides whether you are married.
2. Collect every W-2. RSU income is already in box 1 of the W-2 at vest. If either of you changed jobs, there is more than one W-2 per person.
3. Check the cost basis on RSU sales. When vested shares are sold, the 1099-B often shows incomplete cost basis. The basis should include the income already taxed on your W-2. If it does not, the same dollars can be taxed twice.
4. Gather the kids’ details. Social Security numbers for each child, dependent care FSA statements, and the care provider’s tax ID for Form 2441.
5. Run both ways if you are in California above $1 million of taxable income. Ask your preparer for a side-by-side joint and separate comparison, including the community property split.
6. File the California return with the same status. Washington residents have no state wage return for 2026.

Timing rule worth knowing: you can switch from separate returns to a joint return later by amending with Form 1040-X, but once you file jointly you cannot switch to separate returns after the due date has passed (Pub 501).

Common questions

Can I claim my husband or wife as a dependent?

No. Under IRS rules a dependent is a qualifying child or a qualifying relative, and a spouse is neither. If one spouse has little or no income, the way to count them is to file a joint return, which gives you the $32,200 joint standard deduction for 2026 and the wider joint brackets. For a stay-at-home parent the joint return is almost always the right answer.

Can unmarried partners file taxes together?

Not federally. A joint federal return requires a legal marriage on the last day of the year. Registered domestic partners in California are not married for federal purposes and file as single or head of household on the federal return, but they must file as married/RDP, jointly or separately, on the California return (Pub 555 and FTB Form 540 instructions).

Does filing jointly change our 401(k) or backdoor Roth plans?

Not much at this income. The $24,500 401(k) limit for 2026 is per person regardless of filing status. Joint MAGI is far above the 2026 Roth IRA phase-out of $242,000 to $252,000, so direct Roth contributions are off the table either way and the backdoor Roth route is the usual path.

What to write down for your kids

Filing status looks like a box on a form, but the reasons behind it are a family decision: how you share income, who carries which risks, and why you chose one return over two. Write a short note each year with the status you chose, the numbers you compared, and who prepared the return. When your children are adults filing their own first joint return, that note is a better teacher than a spreadsheet they have never seen. Conversations fade. Documentation compounds.

Next step

Before your 2026 return, ask your preparer for a joint vs. separate comparison if your California taxable income is above $1 million, and set estimated payments to cover the RSU withholding gap. If you want a second set of eyes on both, our tax management team can review them as part of a Tax & Wealth Assessment. Related reading: what happens if you file as single when married, how a stay-at-home parent’s taxes work, how the standard deduction relates to MAGI, and our retirement and employee benefits work.

This article is general education, not individual tax advice. The right filing status depends on your family’s full picture, including how your income and equity are characterized under community property law.

Written by

Kevin Luu

Co-Founder and Chief Learning Officer, Bright Advisers

Kevin has advised high-income W-2 tech and biotech families since 2015, and leads the education-first Age Five Family Office from Brea, California.

Connect on LinkedIn →  · About Kevin