Are you newly married or about to get married this year? Congratulations. But somewhere between the honeymoon and unpacking, there’s a list of tax changes that most couples simply don’t think about. And that’s exactly the problem. The IRS treats marriage as a significant life event, which means your tax situation changes whether you’re ready for it or not. For many couples, especially dual-income earners, missing these changes can mean a surprise tax bill in April.

The good news is that many of these issues are straightforward to address now, before the year ends. Handling them proactively keeps you from scrambling in March or discovering problems when you file. Here’s what you need to know.

Your filing status just changed, even if nothing else did

Your marital status on December 31st determines your filing status for the entire tax year. Even if you get married in May, June, or later this year, you’ll file as married for 2026. This single change affects your tax brackets, standard deduction, and eligibility for certain credits, which is why it matters far more than most couples realize.

For most married couples, filing jointly is the right move. You’ll benefit from wider tax brackets, a higher standard deduction, and access to valuable credits like the child tax credit and education credits that may not be available if you file separately. Filing jointly also simplifies your return and often results in a lower overall tax bill.

However, there are situations where married filing separately deserves consideration. If one spouse is pursuing income-driven repayment on federal student loans, filing separately can keep that spouse’s income lower on their individual return, which directly lowers their monthly payment obligation. Similarly, if one spouse has significant liability concerns or anticipates collection issues, filing separately can provide a layer of protection. These scenarios are nuanced, and the decision hinges on your specific circumstances. Before you choose to file separately, talk to your CPA. The tax savings or liability protection may be real, but so are the downsides you might not see coming.

The withholding problem no one warns you about

Once your filing status is settled, the next thing to address is your withholding. And for two-income couples, this is where the most expensive surprises tend to hide.

Federal income tax is a pay-as-you-go system. Your employer withholds tax from each paycheck based on the information you provide on Form W-4, and the default withholding tables were designed with a single income in mind. When two earners file jointly, their combined income gets taxed at rates that reflect the full household total, but each employer is only withholding based on one salary in isolation.

Here’s what that looks like in practice: if you each earn $70,000, your household income is $140,000. The marginal rate that applies to the top portion of $140,000 is higher than what either employer assumed when calculating withholding for a $70,000 earner on their own. Unless you both update your W-4s to account for this, you will likely end up owing money next April. 

The IRS has a free withholding estimator at IRS.gov that walks through this calculation. It takes about ten minutes and tells you exactly how much additional withholding to request on each spouse’s W-4. Federal underpayment penalties are modest but entirely avoidable, and discovering a large tax balance due on April 15th is a stressful way to start a marriage.

One additional note for couples with self-employment income or significant non-W-2 earnings: estimated quarterly payments may also need to be revisited. Underpaying throughout the year can trigger penalties even if you settle the full balance when you file.

Update your name and address in the right order

If you changed your name after marriage, the Social Security Administration needs to hear about it before you file your tax return. Your name on the return must match what is on file with Social Security. A mismatch will delay your refund and can generate a notice that takes time and paperwork to resolve.

The fix is straightforward: file Form SS-5 with the SSA to update your records. Do this first, then update your name with your employer for W-2 purposes.

Address changes are simpler. If you moved, file Form 8822 with the IRS to update your address on file. This is not just administrative tidiness. Notices, refund checks, and correspondence go to the address the IRS has on record. If a notice sits undelivered at an old address, response deadlines keep running regardless.

Healthcare coverage gets more complicated

Marriage is a qualifying life event that allows both spouses to make mid-year changes to employer-sponsored health plans. That flexibility is valuable, but the decisions that follow it have real tax implications.

If you both carry employer-sponsored coverage, consider whether it makes more financial sense to consolidate onto one plan or maintain separate coverage. The answer depends on the quality and cost of each plan, but do not overlook the tax treatment of premiums. Employer-paid premiums are excluded from your taxable income. If one spouse’s employer offers a significantly better or cheaper plan, consolidating may reduce your combined tax liability in addition to simplifying your coverage.

If either spouse has a Health Savings Account (HSA), marriage changes the contribution limits and household eligibility rules in ways that are easy to mishandle. HSA eligibility requires enrollment in a High Deductible Health Plan (HDHP). If one spouse moves to a non-HDHP plan, they can no longer contribute to their HSA going forward, and the timing of that change matters for calculating the annual contribution limit. Excess HSA contributions carry a 6% excise tax, so getting this right before year-end is worth a quick review.

Dependents: who claims whom, and what changes

If either spouse has children from a prior relationship, the dependency picture becomes more layered. Dependency exemptions have been eliminated under current law, but the child tax credit, the child and dependent care credit, and head-of-household filing status all hinge on who qualifies as a dependent on whose return.

Generally, the custodial parent claims the child unless there is a written agreement or court order directing otherwise. That arrangement may have worked cleanly when each parent filed as a single individual, but it interacts with your new joint return and your spouse’s income in ways that can affect credit eligibility. The child tax credit, for instance, phases out at higher income levels. Adding a second income to the household may reduce or eliminate credits that were previously available.

If your spouse has no children but you do, updating your W-4 to reflect dependent-related credits is one of the withholding adjustments that often gets missed in the transition.

A note on state taxes

This article focuses on federal taxes, but your state may have its own wrinkles. Some states do not conform to federal filing status rules. A small number of states require or allow separate returns regardless of federal treatment. If you moved to a new state in connection with your marriage, you may have a part-year residency situation on both state returns. These scenarios are worth confirming before you assume your federal approach carries over cleanly.

What to do now

The adjustments covered here are time-sensitive because withholding corrections and benefits elections need to happen before year-end to affect your current-year return. Waiting until you sit down to file in February or March means absorbing any underpayment consequences rather than preventing them.

Getting these details right in year one sets a much cleaner foundation for everything that follows. If you have questions about what you need to do we’re glad to work through it.