Why Your Bonus Feels Overtaxed (It Isn't — But Fix This Anyway)

Every bonus season produces the same reaction: “They taxed half my bonus!” Here’s what actually happened — and the two situations where you genuinely should act.

Withholding is not tax

Your bonus is ordinary income, taxed at exactly the same rates as your salary when the return is filed. What’s different is the withholding: supplemental wages (bonuses, commissions, RSU vests, severance) are typically withheld at a flat federal rate — 22% for most people — plus Social Security, Medicare, and state withholding. Stack federal, FICA, NJ or NY, and sometimes local, and 35–40% of the check disappears. It feels like a penalty tax. It’s a prepayment, reconciled in April like everything else.

If the flat withholding over-collected relative to your real bracket, the refund returns it. Annoying, but self-correcting.

The trap that runs the other direction

Now the version that costs people money: if your marginal bracket is higher than 22% — true for most households above roughly $200K — then flat 22% withholding on a large bonus is under-collecting. A $100,000 bonus for someone in a 35% bracket arrives $13,000 light on federal tax alone. Multiply across a big RSU vest or a banker’s bonus and April delivers a five-figure balance due plus, potentially, underpayment penalties.

This is the single most common “surprise tax bill” mechanism we see for high-earning W-2 households — and it’s entirely predictable in advance.

What to do about it

Step 1 — Know your real marginal rate. If it’s above 22%, every supplemental check is under-withheld by the difference.

Step 2 — Fix it through withholding, not estimates, when you can: a W-4 adjustment (line 4c extra withholding) in the months after a big bonus, or asking payroll to withhold at a higher rate on supplemental runs if they allow it. Withholding counts as paid evenly all year — it can cure earlier quarters retroactively.

Step 3 — Very large supplemental payments (above the seven-figure threshold) are mandatorily withheld at the top rate — those take care of themselves.

Step 4 — Check the state side: NJ and NY have their own supplemental rates, and NY commuters should confirm the bonus is being sourced and withheld to the right state — bonuses tied to a prior year’s work follow that year’s workday allocation.

Step 5 — Don’t spend the gross. The reliable habit: treat the net as real and route a slice of any large bonus to the tax reserve until your projection says otherwise.

The planning upside

A bonus is also a lever: it can fund the 401(k) to the max early (watch the match true-up rules), fill the backdoor Roth, or absorb a deductible HSA contribution. Ten minutes of planning before the check hits turns “why is my bonus taxed so hard” into “my bonus just finished my retirement funding for the year.”

Romanchuk CPA LLC is a fully virtual CPA firm serving individuals and business owners nationwide since 2014, with NJ/NY depth. Book a consultation at rfg.tax.

This article is general information, not tax advice for your specific situation. Figures adjust annually — verify current amounts.