What Marriage Does to Your Retirement Accounts
Filing status is an input to almost every retirement account rule, so a wedding silently rewrites what each of you may contribute, deduct, and convert. Four changes matter.
The Roth door moves — and married filing separately slams it Roth IRA eligibility phases out over a MAGI band that is different for joint filers than for singles (section “Roth IRA”), so marriage can open the door for a lower earner and close it for two high earners who were each individually eligible. The vicious case is the third status: for married filing separately the Roth phase-out band runs from $0 to $10,000, and unlike almost every other threshold in the Code it has never been indexed ( IRC §408A(c)(3)(B), “Roth IRAs”). A separated-but-not-divorced spouse who elects married-filing-separately to escape joint liability (section “The Marriage Penalty and the Marriage Bonus”) has therefore also eliminated their Roth contribution — unless they lived apart from their spouse for the entire year, in which case they are treated as single for this purpose. The same $10,000 band caps the traditional IRA deduction for a separate filer covered by a workplace plan. Check this before choosing the status, not after.
The backdoor Roth pro-rata rule is per person, not per couple The pro-rata calculation that spoils a backdoor Roth conversion aggregates that individual’s IRA balances ( IRC §408(d)(2), “Taxability of beneficiary of employees’ trust”, section “Backdoor Roth IRA”); it does not look across a joint return. One spouse’s seven-figure rollover IRA has no effect on the other spouse’s clean backdoor conversion. The planning move follows directly: when only one of you can do backdoor conversions cheaply, park the pre-tax rollover IRA with the other spouse, or roll it into an employer plan that accepts it.
Marriage creates a retirement account out of nothing A spouse with no earned income can still fund an IRA against the working spouse’s compensation on a joint return (section “Individual Retirement Arrangements (IRAs)”) — so the stay-at-home spouse who was a tax shelter in section “The Marriage Penalty and the Marriage Bonus” is also an extra tax-advantaged account, every year, for as long as one of you works. Note the asymmetry the divorce chapter inherits: this contribution room exists only while you are married and filing jointly, and post-2018 alimony does not replace it (section “Alimony After the TCJA”).
Social Security claiming becomes a joint decision, and it is survivor insurance Once married, the higher earner’s claiming age stops being a bet on their own longevity and becomes a purchase of protection for whichever of you lives longer: the survivor benefit is based on what the deceased spouse was receiving, so every month the higher earner defers past full retirement age raises the floor under the survivor for the rest of their life. Run it as one decision, not two — higher earner delays toward 70, lower earner claims earlier if cash flow requires it. The mechanics, including the deemed-filing rules and why survivor benefits escape them, are in section “Social Security”; the reason this matters more than the arithmetic suggests is in section “The Widow’s Penalty”.
One account crosses both chapters. An HSA (section “Health Savings Account (HSA)”) passes to a surviving spouse as their own HSA, intact and still tax-free; named to anyone else, it is fully taxable income to that beneficiary in a single year. It is the one account where the spousal beneficiary designation is worth more than the will, the trust, or any argument about fairness.