Bonus Withholding and Estimated Tax in a Big Fund Bonus Year

What do I pay by January 15 and April 15?

To avoid the federal penalty, withholding plus estimated payments must reach the smaller of 90% of this year's tax or last year's tax (110% of it if last year's adjusted gross income was over $150,000), spread over four due dates, the last on January 15, 2027. The rest of the bill is due by April 15. Extra withholding from December paychecks counts as paid evenly all year; an estimated payment counts only from the day you make it.

Is my case simple?

Your case is simple if your only big item is a W-2 bonus, last year's return is filed, and your withholding already passes the prior-year target. Your case needs a full projection if you have K-1 income, a deferred tranche vesting, two employers, a spouse with wages, a move between states, or California adjusted gross income at or above $1,000,000. A full projection covers federal and state tax together and sets the W-4 and estimate amounts before the last paychecks of the year; see our hedge fund services.

What to gather:

• your latest pay stubs, with year-to-date wages and withholding;
• last year's federal and state returns;
• K-1 estimates and tax distribution notices from each fund or deal;
• vesting and payout schedules for any deferred bonus;
• estimated payments already made this year, with dates.

Why was so little withheld from my bonus?

Payroll withheld at a flat supplemental rate, not at your tax rate. Supplemental wages are pay outside your regular salary, such as bonuses and commissions. The flat rate is often far below what a large bonus actually costs you.

A W-2 bonus is ordinary wages, taxed at your regular rates on your return. There is no separate "bonus tax rate". The rates you see on the pay stub are only withholding rates set out in Publication 15:

The threshold counts all supplemental pay from businesses under common control, so a management company and an affiliated adviser under common control count as one payer.

The gap comes from three places. The first slice of the bonus is withheld at the flat rate even if your top bracket is higher. Federal withholding does not cover state tax, and state withholding on the bonus may fall short of your top state rate. Nothing at all is withheld on K-1 income, for income tax or the 3.8% net investment income tax. And the Additional Medicare Tax is often under-withheld (next section).

Carry, or an incentive allocation (the hedge fund form of carry), is different. It reaches you as partnership income on a Schedule K-1, nothing is withheld, and you are taxed on your share whether or not the fund distributes cash (Schedule K-1 instructions). For the holding-period rule on carry, see the three-year rule for carried interest.

Why does payroll miss the Additional Medicare Tax?

Each employer withholds the 0.9% Additional Medicare Tax only on the wages it pays you above $200,000 in the calendar year, whatever your filing status (Topic 560). Your actual tax uses your filing status and all your wages.

Under-withholding happens when:

• your spouse also has wages, so your joint wages pass $250,000 while neither employer reaches its $200,000 trigger alone;
• you had two employers in one year, and each starts counting from zero (see leaving a fund with unvested pay and carry);
• you are married filing separately, where the tax starts at $125,000 but withholding still waits for $200,000.

You figure the tax on Form 8959. Topic 560 says you can cover it with extra income tax withholding on Form W-4 or with estimated payments.

Will I owe an underpayment penalty? How the safe harbor works

You avoid the federal penalty (the "safe harbor") if your withholding and timely estimated payments reach the smaller of two targets, paid in four equal parts (Publication 505; 26 USC 6654(d)):

• 90% of this year's tax; or
• 100% of last year's tax, raised to 110% if last year's adjusted gross income was more than $150,000 ($75,000 if married filing separately this year). This target works only if you filed a return for last year covering all 12 months (26 USC 6654(d)(1)(B)); if you moved to the US this year or filed no return last year, only the 90% target is available.

There is no penalty if this year's tax minus withholding is under $1,000 (26 USC 6654(e)).

You can skip the January payment if you file the return and pay all tax by January 31, or the next business day if it falls on a weekend (February 1, 2027 for this tax year; Publication 505). This is rarely possible when you wait for K-1s.

In a big bonus year, the prior-year safe harbor is usually the smaller target, and it is a fixed number once last year's return is filed. If that return is still on extension, see late fund tax forms. Meeting it removes the penalty, not the bill: everything else is due by April 15.

What the penalty is: interest at the IRS underpayment rate on each quarter's shortfall, from its due date until paid or April 15, whichever comes first (26 USC 6654(b)). It is figured separately for each period. Tax still unpaid after April 15 adds a failure-to-pay penalty of 0.5% a month, up to 25% (IRS).

Can extra withholding late in the year fix an earlier shortfall?

Yes. Federal withholding is treated as paid in equal parts on each of the four due dates, unless you choose to show the actual dates (26 USC 6654(g)). So extra tax withheld from a December paycheck also covers April, June and September. An estimated payment counts only from the day you make it.

How to use this rule:

1. Project the year: bonus, salary, K-1 estimates, and any deferred pay that vests or pays out this year.
2. Compare withholding to date plus expected withholding with the smaller target above.
3. Give payroll a new Form W-4 with an extra amount per paycheck in Step 4(c) (extra withholding) for the remaining pay periods (Publication 505).
4. Ask payroll whether it can withhold more on the bonus itself. Under the flat-rate method Publication 15 allows 22% only, so the extra may have to come from regular paychecks.
5. If not enough paychecks are left, make an estimated payment as early as possible. It stops interest from the date paid, but it does not count back to earlier quarters.

The fund's tax distribution didn't cover my tax on carry. Why, and what now?

The fund figures its tax distribution at an assumed rate on its own estimate of your income, so it can fall short of your real bill. A tax distribution is cash the partnership agreement allows, not a payment to the IRS. The agreement sets the assumed tax rate, which income counts and when cash is paid. Your own bill can be larger: your state, the 3.8% tax, income allocated late in the year, or a K-1 that differs from the fund's estimate.

You owe tax on your share of partnership income whether or not it was distributed (Schedule K-1 instructions). The gap is paid through withholding or estimates, as above. How a fund or deal vehicle sets its distributions is covered in SPV and co-invest vehicle tax returns. If the K-1 arrives after April 15, see late fund tax forms.

What about state estimated tax in New York, New Jersey, Connecticut and California?

Each state has its own tests. Do not assume the federal rule carries over.

The California rule matters most in a big year: with no prior-year safe harbor, you must estimate this year's California tax well. The New Jersey figures come from the latest published form. Other states differ again. If you moved during the year, see state tax on deferred pay after a move.

What can I still do before December 31 to lower this year's bill?

Few steps still change this year's tax: pre-tax 401(k) deferrals from the paychecks left, charitable gifts, and, for partners, a state pass-through entity tax election made by the state's deadline. A deferral election for next year's bonus and a move change later years, not this one.

• 401(k) deferrals. The elective deferral limit is $24,500, counting deferrals at every employer this year; whatever room remains can only come from paychecks still to be paid. If you are 50 or older and last year's wages from the same employer were above the line in 26 USC 414(v)(7), catch-up contributions must be Roth, so they do not lower this year's income. Partners should see self-employment tax for fund managers.
• Next year's bonus (changes next year). Elections to defer future pay usually must be made before the year the pay is earned. See deferred bonus at a fund manager.
• Charitable gifts. For itemizers, gifts now count only above 0.5% of adjusted gross income (26 USC 170(b)(1)(I)). In the top bracket, total itemized deductions are also cut by 2/37 of the smaller of those deductions or the amount by which your taxable income plus those deductions exceeds the start of that bracket (26 USC 68). For an itemizer, a large gift can still reduce tax, but by less than its face value.
• Paying state tax early. Paying a January state estimate in December stops state interest sooner but rarely lowers federal tax at this income: the state and local tax deduction limit of $40,400 shrinks by 30% of modified adjusted gross income above $505,000, to no less than $10,000 (26 USC 164(b)).
• A move (rarely changes this year). Pay for work done while you lived in a high-tax state can stay taxable there after you leave. See state tax on deferred pay after a move; for when residency ends, see moving to Florida or Texas as a fund manager.
• Partners only. A state pass-through entity tax election at the management company can move state tax to the entity, but only if made by the state's deadline; New York's falls on March 15 of the tax year (New York PTET). See the pass-through entity tax election.

Which income do the net investment income tax and Additional Medicare Tax reach?

The 3.8% net investment income tax applies to the smaller of your net investment income or your modified adjusted gross income above $200,000 ($250,000 married filing jointly, $125,000 married filing separately) (Publication 505). Wages are not net investment income. Carry and co-invest income from a fund that trades financial instruments or commodities can be, because that business is named in 26 USC 1411(c)(2); investment gains and dividends are as well.

The 0.9% tax reaches wages and self-employment income above the thresholds in the table above. It does not reach investment income.

The two interact. Lower wages this year, through a pre-tax (not Roth) 401(k) deferral or a bonus deferral election made before the year began, lower your adjusted gross income, so they can also shrink the 3.8% tax when your investment income is larger than the excess over the threshold. Confirm this with the Form 8960 calculation rather than assuming it.

I already got a penalty notice. Can it be reduced?

It can be, in two ways. When most of your income arrived late in the year, the annualized income installment method, a schedule attached to Form 2210, can lower the required payments for earlier quarters (Form 2210 instructions). The IRS can also waive the penalty for a casualty, disaster or other unusual circumstance, or if you retired after age 62 or became disabled in the year or the year before and the underpayment had reasonable cause (26 USC 6654(e)(3)). For how the annualized method works step by step, see S corporation estimated tax payments.

Example

Round, illustrative figures in US dollars. Federal tax only.

A bonus over the million-dollar mark

Dana's employer pays a $1,500,000 bonus in February and uses the flat rate. Withholding on the bonus: 22% of $1,000,000 ($220,000) plus 37% of $500,000 ($185,000), $405,000 in all. Salary withholding adds $70,000 over the year, for $475,000.

Last year Dana's tax was $400,000 and adjusted gross income was over $150,000, so the prior-year target is 110%, or $440,000. Withholding of $475,000 passes it: no underpayment penalty. Dana's projected tax this year is $640,000, so about $165,000 is still due by April 15.

A shortfall found in November

Same target of $440,000, but suppose Dana's bonus was smaller and total projected withholding is $360,000: $80,000 short.

• Estimated payment on January 15. It is credited to the earliest shortfalls, but only from the day paid. The first three periods were each $20,000 short, and interest runs on each from its due date to January 15. The fourth period is paid on time.
• Extra withholding of $80,000 from December paychecks. It is treated as paid $20,000 on each of the four due dates. No period is short, and there is no penalty.

A carry year with a tax distribution

Dana's K-1 also shows $2,000,000 of long-term carry gain. The fund's tax distribution is $400,000, figured at the fund's assumed rate. Federal tax at 20% plus the 3.8% tax is about $476,000 before any state tax. The $76,000 difference, plus state tax, is Dana's to pay. If the K-1 income was not in the plan, the prior-year target above still protects against the federal penalty, but the balance is due April 15.

Different for you?

• Bonus plus K-1 income, or a deferred tranche paying out in the same year: the projection needs every source at once. See our hedge fund services.
• You moved to the US this year, or filed no US return last year: the prior-year target is not available. See our cross-border tax services.
• K-1s that arrive after April 15: see late fund tax forms.
• Carry held less than three years: see the three-year rule for carried interest.
• You want to defer more of next year's bonus: see deferred bonus at a fund manager.
• You changed firms this year: see leaving a fund with unvested pay and carry.
• You moved, or plan to, before a payout: see state tax on deferred pay after a move and moving to Florida or Texas as a fund manager.
• You are a partner of the management company: see the pass-through entity tax election and self-employment tax for fund managers.
• A penalty notice already arrived, or you want the annualized method: see S corporation estimated tax payments, or individual tax services for help with the reply.