Marriage Financial Decision Modeling

How this engine works

You enter your own figures; the engine models two scenarios side by side and shows the twelve-month difference between them. The outputs are estimates built from your inputs and documented assumptions — not predictions, and not advice. Mood and stress are self-reported context that adjust the wording of the summary, nothing else. Inputs are processed in your browser. The full methodology, including what the engine does not claim, is on the Decision Center.

Step 2: Decision Forge — compare assumptions

Decision scenarios with reflection prompts

Each scenario in the tool above presents two options drawn from this event and models them side by side from the figures you entered. Before the comparison, the page names a cognitive-bias concept as an educational reflection prompt. It is a general prompt attached to the scenario rather than a finding about you: the page does not test whether the concept applies to your situation, and it does not indicate which option you should choose.

Self-reported context at decision time

The page does not create a psychological profile. Mood and stress may tailor wording and general next-step suggestions. They do not change the entered financial values or scenario math. They do not establish decision readiness. The named bias concept is a general reflection prompt; the page does not detect bias, assess decision capacity, diagnose a condition, or predict outcomes.

The clocks that start on the wedding day

Most of what marriage changes, it changes gradually. Four things do not. Each is fixed on a date by a statute or a plan document rather than by the two of you, and two of them are counted from the wedding itself rather than from the day you get round to the paperwork.

The marriage penalty is narrower than you have been told, and worse where it bites

For 2026 the married-filing-jointly brackets are exactly double the single brackets all the way through the 32 percent rate. The doubling breaks in one place only: the top.

So a married couple reaches the 37 percent rate at $768,700 of taxable income, where two unmarried people would each reach it at $640,600. Published claims that the brackets stop doubling at 32 or 35 percent are wrong for 2026 (Rev. Proc. 2025-32).

The brackets are not the whole story, and the part that is left out is the part that grows. The Net Investment Income Tax and the Additional Medicare Tax apply above $250,000 for a couple filing jointly against $200,000 for a single filer — not double, and not indexed for inflation. Those thresholds have been fixed since 2013, so that penalty widens every year without anyone legislating it.

One more figure worth having straight: married filing separately is not the same as filing single at the top. The 37 percent rate begins at $384,350 for a separate filer — half the joint threshold, not the single one. This catches people who assume filing separately reproduces their pre-marriage position.

The 2026 numbers that change on the wedding date

The health-insurance condition nobody mentions

Marriage opens a 60-day special enrolment period on the marketplace. What is almost universally omitted is the condition attached to it: at least one spouse must have had qualifying health coverage for one or more days in the 60 days before the marriage. A couple where neither person was insured in the two months before the wedding does not qualify, which is precisely the couple most likely to be looking.

There are narrow exceptions — living abroad or in a US territory during that window, membership of a federally recognised tribe or Alaska Native Claims Settlement Act shareholder status, or living in an area with no marketplace plan available. Check them before assuming the window is open (45 CFR 155.420).

Portability: the election that is easy to make and easy to lose

The unlimited marital deduction means a transfer to a US-citizen spouse passes free of estate tax. What is not automatic is portability — carrying the first spouse’s unused exclusion over to the survivor. It must be elected on a timely filed Form 706, due nine months after death with a six-month extension available.

If the estate had no filing requirement in the first place, there is a simplified route: the estate may file to elect portability up to the fifth anniversary of the death. That window was extended from two years in July 2022, and a great deal of published guidance still shows the old figure — which matters, because a family told they have missed a two-year deadline may not ask again (Rev. Proc. 2022-32).

A separate point worth flagging: the unlimited marital deduction applies to a US-citizen spouse. Where the surviving spouse is not a citizen, a qualified domestic trust is generally required, and this is routinely left out of general-audience guidance.

Student loans: the calculation changed in 2026

How marriage affects an income-driven payment depends on the plan and on how you file, and the landscape moved underneath this question during 2026.

On the Repayment Assistance Plan, Income-Based Repayment and Pay As You Earn, filing jointly means joint income is used and filing separately means the borrower’s income alone. Income-Contingent Repayment is the exception: it uses joint income when both spouses are on ICR, whatever the filing status. The Repayment Assistance Plan became available for new loans from 1 July 2026, and borrowers on phased-out plans have until 1 July 2028 to choose among it, the Tiered Standard plan and IBR. SAVE has been terminated, so any guidance describing SAVE spousal-income rules is describing a plan that no longer exists.

Filing separately to reduce a loan payment is a real strategy and an incomplete one as usually presented. It trades against the Earned Income Tax Credit, education credits, and the student loan interest deduction, none of which are available to a separate filer. Run both returns before choosing; the payment saving is easy to see and the tax cost is not.

Name changes have an order

Social Security first, then the driver’s licence, then the passport. State motor-vehicle agencies verify names against Social Security records, so a DMV visit before the SSA record updates will usually fail and have to be repeated.

SSA requires proof of the legal name change, proof of identity, and proof of citizenship if not already on record, using Form SS-5. Originals or certified copies only — photocopies and notarised copies are not accepted. There is no fee. And SSA does not notify other agencies on your behalf, so every other update is yours to make.