Original data · Equity compensation
The RSU withholding gap index: where the 22% rule breaks
50 computed salary-and-vest scenarios for 2026: where the flat 22% supplemental withholding matches your real tax, where it breaks, and by how much.
The short answer
The flat 22% withheld on RSU vests covers your real tax only while your salary keeps you inside the 22% bracket. We computed 50 salary-and-vest combinations for 2026: the rule visibly breaks around a $150,000 salary, and at $300,000 every vest is under-withheld by 13 cents on the dollar — $1,300 per $10,000 vested. Married-filing-jointly households under $150,000 are over-withheld instead.
Find your cell: RSU withholding-gap calculator →
What the index shows
- The 22% rule breaks at about $150k. Single filers with salary under ~$150,000 are roughly fine on small vests (gap ≤ 2% of vest value). Above that, every vest is under-withheld, and the shortfall grows with salary faster than with vest size.
- At $250k salary, even a small $10,000 vest is 10% under-withheld — a $1,000 surprise on a vest most people assume is “already taxed.”
- Worst case in the index: 13 cents on the dollar. At a $300,000 salary, every vest is short by 13% of its value ($1,300 per $10,000 vested) because the full vest stacks into the 35% bracket while payroll withholds 22%.
- The marriage asymmetry. A married couple filing jointly at $100,000 household salary is over-withheld at 22% — about $1,000 back per $10,000 vest (their true slice is 12%). Same vest, opposite sign, purely from bracket position. The gap only turns positive for MFJ households above ~$150k, and stays modest (≤ 4.6% in this grid).
- Bracket position dominates vest size. For a single filer, moving salary from $150k → $300k grows the gap on a $50k vest from $1,000 to $6,500 (6.5×). Growing the vest 5× at a fixed salary rarely doubles the gap rate.
The per-vest mechanics behind every cell: the RSU withholding-gap guide →
The index
Gap = true federal income-tax slice on the vest minus the 22% flat withholding, as % of vest value (true slice rate | gap in dollars). Standard deduction, single, no other income, TY2026.
Single filers
| Salary \ Vest | $10k | $25k | $50k | $100k | $200k |
|---|---|---|---|---|---|
| $100k | 0% (22.0% | $0) | 0.3% (22.3% | $64) | 1.1% (23.1% | $564) | 1.6% (23.6% | $1,564) | 5.5% (27.5% | $10,964) |
| $150k | 2.0% (24.0% | $200) | 2.0% (24.0% | $500) | 2.0% (24.0% | $1,000) | 4.6% (26.6% | $4,570) | 8.5% (30.5% | $16,900) |
| $200k | 2.0% (24.0% | $200) | 4.3% (26.3% | $1,070) | 7.1% (29.1% | $3,570) | 9.4% (31.4% | $9,400) | 11.2% (33.2% | $22,400) |
| $250k | 10.0% (32.0% | $1,000) | 10.3% (32.3% | $2,580) | 11.7% (33.7% | $5,830) | 12.3% (34.3% | $12,330) | 12.7% (34.7% | $25,330) |
| $300k | 13.0% (35.0% | $1,300) | 13.0% (35.0% | $3,250) | 13.0% (35.0% | $6,500) | 13.0% (35.0% | $13,000) | 13.0% (35.0% | $26,000) |
Married filing jointly
| Salary \ Vest | $10k | $25k | $50k | $100k | $200k |
|---|---|---|---|---|---|
| $100k | −10% (12.0% | −$1,000) | −10% (12.0% | −$2,500) | −6.6% (15.4% | −$3,300) | −3.3% (18.7% | −$3,300) | −1.1% (20.9% | −$2,172) |
| $150k | 0% (22.0% | $0) | 0% (22.0% | $0) | 0% (22.0% | $0) | 0.1% (22.1% | $128) | 1.1% (23.1% | $2,128) |
| $200k | 0% (22.0% | $0) | 0% (22.0% | $0) | 0.3% (22.3% | $128) | 1.1% (23.1% | $1,128) | 1.6% (23.6% | $3,128) |
| $250k | 2.0% (24.0% | $200) | 2.0% (24.0% | $500) | 2.0% (24.0% | $1,000) | 2.0% (24.0% | $2,000) | 2.6% (24.6% | $5,140) |
| $300k | 2.0% (24.0% | $200) | 2.0% (24.0% | $500) | 2.0% (24.0% | $1,000) | 2.0% (24.0% | $2,000) | 4.6% (26.6% | $9,140) |
Negative = withholding exceeds the true tax slice — the 22% rule over-collects for these households.
How we computed this
Computed with TaxGhost’s deterministic federal tax engine (version 2026.2.2) using 2026 parameters from Rev. Proc. 2025-32. Each cell: one RSU vest at the stated value, salary as stated, standard deduction, no other income, single or MFJ as labeled. ‘True tax on the vest’ is the marginal federal income-tax slice attributable to the vest (total income tax with the vest minus without it) — Social Security and Medicare on vest income are withheld separately in payroll and are not part of this index. Withholding modeled at the flat 22% supplemental rate (IRS Pub 15-T); the mandatory 37% rate above $1M of supplemental wages is outside the grid. No state tax. The index is a planning estimate, not tax advice.
Computed August 2, 2026 · re-verified August 3, 2026.
Find your cell
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FAQ
Is 22% withholding enough for RSUs?
Only inside the 22% bracket. At a $100,000 salary the gap is 0–1.6% of the vest; at $300,000 it is a flat 13% — $1,300 per $10,000 vested. The tables above have your cell.
Why does salary matter more than vest size?
The vest stacks on top of your salary. Moving from $150k to $300k salary grows the gap on a $50k vest from $1,000 to $6,500; growing the vest 5× at a fixed salary rarely doubles the rate.
Can RSU withholding be too much?
Yes. Married filing jointly at a $100,000 household salary, 22% withholding over-collects by about $1,000 per $10,000 vest — a refund, not a bill.
A guide answers this once. TaxGhost answers it every month — the monitor recomputes what you owe each time your income changes.
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