★ Tax year 2026 · Federal + 50 states ★
RSU BUDDY
Your vest gets withheld at a flat rate that has nothing to do with your actual tax bracket. This works out what you'll really owe, and whether you need to send the IRS a check before April.
RSU BUDDY v2.0
VESTYMOOD: UH OH
send the IRS a check!
Player 1 — who you are
Leave at zero unless your city or county levies its own income tax.
Vesting events this year
Fills in the price on any vest that doesn't have one yet.
Vest dateSharesPrice
Total vest income$609,000
Your other income
Also counts toward the $1M supplemental threshold.
Pre-tax deferrals.
Self-employment, rental, RSU sale gains.
Interest, dividends, capital gains. Subject to the 3.8% NIIT.
What's already been withheld
Only fill this in if your paystub shows something other than 22% (or 37% above $1M).
Last year's return — for safe harbor
Form 1040, line 24.
Line 11. Over $150k triggers the 110% rule.
Deductions
Leave at zero to take the $16,100 standard deduction.
You are $79,129 short.
Below safe harbor — penalty risk
That is the balance you would owe across federal, state and local when you file, on top of everything already withheld.
Already withheld $248,265Still owed $79,129Total income tax $327,395
Federal
Your vest is withheld at a flat 22%, but your top federal bracket is 37%. That 15-point gap on $609,000 of vest income is the single biggest reason people owe money in April.
CA
California withholds vest income at 10.23% but taxes you at a 12.3% marginal rate. 10.23% on stock/RSU and bonus income paid separately (EDD DE 231PS).
Payroll
CA SDI (1.3%, no wage cap) takes another $10,647 out of your pay. It is not income tax, so it does not count toward the balance above.
Data
California has not published 2026 schedules yet, so 2025 brackets are used here. Expect the real numbers to be slightly lower after inflation indexing.
CA
California’s top rate is 13.3%, including the 1% Mental Health Services tax on income over $1M. The 10.23% supplemental rate is a fixed statutory rate and is current for 2026.
FICA
Your wages pass the $184,500 Social Security cap, so vest income above that point escapes the 6.2% tax. Medicare (1.45%, plus 0.9% over $200,000) keeps applying with no cap.
| Vest date | Shares | Price | Income | Fed rate | Fed withheld | CA withheld |
|---|---|---|---|---|---|---|
| Feb 15, 2026 | 700 | $214 | $149,800 | 22% | $32,956 | $15,325 |
| May 15, 2026 | 700 | $231 | $161,700 | 22% | $35,574 | $16,542 |
| Aug 15, 2026 | 700 | $205 | $143,500 | 22% | $31,570 | $14,680 |
| Nov 15, 2026 | 700 | $220 | $154,000 | 22% | $33,880 | $15,754 |
| Total | $609,000 | 22% | $133,980 | $62,301 |
Income tax you owe
| Federal income tax | $243,965 |
| Additional Medicare (0.9%) | $5,571 |
| California income tax | $77,858 |
| Total income tax | $327,395 |
What you have paid toward it
| Federal, withheld on vests | $133,980 |
| Federal, withheld on paychecks | $33,254 |
| Additional Medicare withheld | $5,571 |
| California, withheld on vests | $62,301 |
| California, withheld on paychecks | $13,159 |
| Total paid in | $248,265 |
Balance due when you file$79,129
Social Security + Medicare, already taken from your pay$23,315
Adjusted gross income$794,500
Deduction applied$16,100 standard
Top federal bracket37%
Top CA rate12.3%
Effective rate on your income, payroll tax included44.1%
The IRS charges an underpayment penalty unless your payments hit whichever of these two targets is lower. Hitting it protects you from the penalty regardless of how large your April balance turns out to be.
90% of your projected 2026 tax$224,583
Prior-year ruleenter last year’s numbers
Your target — the lower of the two$224,583
Federal payments on track for the year$172,805
Action
You are $51,778 below the safe harbor. Paying at least that much in estimated tax stops the underpayment penalty clock, even though your April balance will still be $76,731.
Split the $51,778 shortfall across the deadlines that have not passed. Pay it through IRS Direct Pay or EFTPS, choosing “estimated tax — Form 1040-ES” for 2026.
Q1
Apr 15, 2026
—
Deadline passed
Q2
Jun 15, 2026
—
Deadline passed
Q3
Sep 15, 2026
—
Deadline passed
Q4
Jan 15, 2027
$51,778
Pay this next
Tip
Withholding gets treated as though it were paid evenly across the whole year, no matter when it actually happened. An estimated payment only counts from the date you send it. So if you are behind, the cheapest fix is often to raise your paycheck withholding for the rest of the year rather than write a check — it retroactively covers the earlier quarters.