Administrative Triage
The economics above are the interesting part. The following is not interesting, takes an afternoon, and is the difference between a clean first joint return and a rejected one:
- Name change, at Social Security first. If either spouse changes their name, file with the Social Security Administration before you file a return. The IRS matches every name against SSA records, and a mismatch stalls or bounces the return — refund included. The new card takes a couple of weeks; the wedding-to-April window is generous, so there is no excuse for discovering this in filing season.
- Address change, in writing. If either of you moved, tell the post office, your employers, your financial institutions, and the IRS. The IRS wants Form 8822; a forwarding order is not a substitute, because a notice mailed to a stale address is legally delivered whether or not you ever see it, and the response clock runs regardless.
- New W-4s. The regulations demand a fresh Form W-4 within ten days when a change raises your withholding — divorce, above all; after a wedding, update it anyway. Two earners are the problem case: each employer withholds as though its paycheck were the household’s only income, so a couple who each earn comfortably can arrive at April with a bill neither withholding table anticipated. Run the IRS Withholding Estimator once, together, with both W-2s in hand.
- The Additional Medicare Tax gap. The 0.9% surtax ( IRC §3101(b)(2)) starts at $250,000 of combined wages for joint filers, but each employer is only required to withhold it above $200,000 of the wages it pays. Two spouses earning $180,000 apiece have of exposed wages and precisely zero withheld against them — owed at filing that nobody flagged. Cover it with extra withholding on a W-4 or an estimated payment (section “Quarterly Estimated Taxes”).
- Decide the filing status deliberately. Your status for the entire year is set by your marital status on December 31 — marry on the thirtieth and you were married all year. Joint filing usually wins, but “usually” is not “always”: run it both ways the first year, particularly where income-driven student-loan repayment, large unreimbursed medical expenses, or a spouse with old tax liabilities is in play (section “Filing status”, section “The Marriage Penalty and the Marriage Bonus”).
- Consolidate the paperwork now. One folder, physical or otherwise, for both spouses’ W-2s, 1099s, and the prior-year returns each of you filed separately. You will need the prior-year AGI to e-file, and the couple that goes looking for a bank login belonging to a spouse who is travelling in April learns this lesson once.
- Benefits enrollment, within thirty days. Marriage is a qualifying life event, and it opens a special enrollment window — typically thirty days — to add a spouse to medical, dental, and vision, to change health and dependent-care flexible spending elections, and to raise group life coverage without underwriting. Miss the window and you wait for open enrollment. Run the two employers’ plans against each other instead of defaulting to whichever of you enrolled first: the cheaper premium is frequently the worse plan, and a working couple often does better on two individual policies than on one family policy.
The HSA and FSA Collision One benefits interaction destroys a tax advantage silently, and it catches couples every January. A general-purpose health flexible spending account can reimburse the expenses of the enrollee’s spouse, which makes it disqualifying coverage — so the moment one of you enrolls in a general-purpose FSA, the other spouse becomes ineligible to contribute to an HSA, even if that spouse is on their own high-deductible plan and never touches a dollar of the FSA. Two people who each had an HSA before the wedding can both lose eligibility because one of them ticked a box. The fixes are simple once you know to look: elect a limited-purpose FSA (dental and vision only), which is not disqualifying (section “Limited-Purpose Flexible Spending Accounts (LPFSA)”), or skip the FSA entirely.
Two more HSA mechanics change on the wedding day. The family contribution limit — $8,750 for 2026 — is a single limit shared between spouses whenever either of you carries family high-deductible coverage, to be divided however you agree; it is not per person. The 55-and-over catch-up, by contrast, is per person, and it can only be contributed to that person’s own HSA, so a couple over 55 needs two accounts open to claim both (section “Health Savings Account (HSA)”). And the dependent-care account is a household limit as well: $7,500 for joint filers in 2026, halved to $3,750 if you file separately (section “Dependent Care Flexible Spending Account (DCFSA)”).