The $400,000 December: How a Big Bonus Year Gets Planned Instead of Survived
If a big slice of your pay arrives as a year-end bonus, December feels like the month that matters. It is not. The bonus month is when the number gets revealed. The months before it are when the number gets planned for, and we are sitting in them right now. So this issue walks through how a big-bonus year actually gets managed, using the kind of client I work with all the time.
WHAT A BONUS DOES TO YOUR TAXES
The IRS treats a bonus as supplemental wages, and for almost everyone the employer withholds federal tax on it at a flat 22 percent. That rate does not know your salary, your spouse’s salary, or where the bonus actually lands in the brackets. Stack a $400,000 bonus on top of a $180,000 salary and the top of that money is being taxed in the 30s while the withholding sits at 22. The result is a gap that quietly becomes an April surprise, with a penalty conversation attached, for anyone who finds out in April instead of December.
HOW THE YEAR ACTUALLY GETS PLANNED
The work runs on a calendar, not on adrenaline. It starts with a review of last year’s tax return, because the return is the map of how your money actually behaves. Then comes a current-year projection, built on an assumed bonus. Here is the part people miss: the bonus is variable, it moves with company performance, so the projection is built to flex. Nobody is pretending to know the number in August. We are building the machine that can absorb whatever the number turns out to be. When the actual bonus prints in December, the projection gets trued up against the real figure, and the last piece falls into place: a fourth quarter estimated payment, scheduled in that quiet week between New Year’s and the January 15 deadline. Until that date the tax money sits in the money market, earning interest. When you know a bill is coming, you pay it on time, not ahead of time.
WHAT THE PROJECTION UNLOCKS
Knowing the shape of your year by fall is worth more than the payment math. A big bonus year is often the right year to bunch two years of charitable giving into a donor advised fund, to fill every retirement bucket you have access to, and to think twice before adding any other income to the pile. None of those moves work in April. All of them work in November, but only if the projection already exists.
A SIMPLE EXAMPLE
Ben is 36, an engineer in Hilliard, married, $180,000 base with a bonus target around $400,000 that floats with company results. In May, with last year filed, we review the return. In July we build the projection on a deliberately conservative $350,000 bonus. In early December the announcement lands: $400,000. The true-up takes a week, and the federal gap comes out to roughly $19,000 beyond what withholding will cover, because most of the bonus fills the middle brackets before the top of it reaches the 35 percent rate. The estimated payment goes on the calendar for January 12, and the $19,000 waits in the money market until then. Bonus week, Ben also moves two years of planned giving into his donor advised fund, in the year where the deduction works hardest. In April, his return is a confirmation, not a reveal. That is the whole point.
THE WHOLE IDEA
You cannot control the bonus number. The company decides that. What you can control is the shape of the year around it: project on an estimate, true up on the fact, pay on time, and use the big year on purpose while it is still open. The April surprise is optional. Skipping it is a calendar, not a miracle, and it is the kind of calendar worth having someone keep with you.
CLOSER TO RETIREMENT? FILE THIS AWAY
Your last big bonus before retirement deserves its own plan, because it is probably the highest tax bracket you will ever see again. That makes it the single worst year for a Roth conversion and one of the best years for everything deductible: maxed retirement contributions, a donor advised fund holding several years of future giving, and any deferral your employer offers. The year after, when the paycheck stops, the brackets open up and the conversions begin. Sequencing those two years on purpose can be worth more than a decade of investment tinkering.
WORTH A READ
Publication 15: Employer’s Tax Guide, Supplemental Wages (IRS.gov)
What Is a Donor Advised Fund? (Fidelity Charitable)
If your bonus is a big share of your pay and April has surprised you before, reply anytime. Happy to walk through what a projection would look like on your numbers, no agenda.
Curious what working together looks like? There is more at jcsretirementtaxadvisors.com, and if a conversation sounds easier, you can grab 30 minutes on my calendar whenever it suits you.
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This newsletter is for education only and is not tax, legal, or investment advice for your situation. The example is illustrative and figures reflect 2026 federal rules for married filing jointly.