Happily married people are often willing to share their joy with everyone. However, if you indicate “married” on the Employee’s Withholding Certificate or Form W-4, you may encounter unexpected “surprises.”

When you fill in “married,” have you provided your spouse’s income? If not, the company will assume you are the only breadwinner in your family and withold taxes according to married tax rates. As a result, you will have more money in hand each time you get paid, but you will owe a lot of taxes when filing your tax return at the end of the year.

The “standard” approach is to find the additional amount to be deducted from each paycheck based on both spouses’ incomes in the appendix of Form W-4, divide it by the remaining number of paychecks, and then fill it in line 4(c). However, some people face practical difficulties with this approach because the income limit for the lower-earning spouse in this appendix is $120,000. If it exceeds this number, this method will not work. The next option is for you to visit the IRS’ Tax Withholding Estimator Website to obtain the extra withholding amount.

However, after all the effort, if the situation changes next year, you have to start all over again. If the tax is withheld insufficiently, even if it is fully paid when filing taxes, there will still be an estimated tax penalty for insufficient tax withholding.

In fact, there is a simple and useful method: each spouse can withhold taxes as “Single or Married filing separately” but file a joint tax return. This approach is based on the fact that when two spouses’ wages are similar or both very high, there is not much difference in tax liability between filing jointly and separately. You can read this post of mine for analysis, or check the actual difference in my comparison worksheet in the tax return that I provide for every married couple.

This method is simple and easy to implement — just check one box — and it is a permanent solution, as the tax withholding will automatically adjust as your salary increases (or decreases).

A note on supplemental income: The default federal withholding rate on supplemental wages (bonuses, stock vesting, commissions, etc.) is a flat 22%. For dual-income households, this flat rate often under-withholds because by the time the bonus hits, much of your combined income is already being taxed at 24%, 32%, or higher. If your employer allows it, request that supplemental income be withheld at your top marginal tax bracket rather than the default 22%. Alternatively, increase the amount on W-4 line 4(c) to compensate. For supplemental wages exceeding $1 million in a calendar year, the mandatory withholding rate is 37%.

For RSU vesting specifically: Many employers only withhold the default 22% (or the minimum required to cover FICA and income tax) and do not allow you to adjust the rate. In that case, you can handle it manually — at the time of vesting, sell additional shares beyond the automatic sell-to-cover amount and set the extra cash aside to pay taxes. For example, if your top marginal bracket is 32% but the company only withholds 22%, sell enough extra shares to cover the 10% gap. This avoids a surprise tax bill at filing time and is effectively the same as having the correct amount withheld upfront.

Like other aspects of marriage, when each person takes care of their own affairs, the couple will thrive together.

PS: I would like to emphasize that I am suggesting you withhold taxes as married filing separately, not filing taxes separately. Unless there are special circumstances or you request it, filing a joint tax return is generally a good choice, at least in terms of saving filing fees.