With RSU tax planning, Modera Wealth Management works out the tax bill on each restricted stock unit vest before it lands and decides which account the vest cash fills next. Employers withhold a flat 22 percent federal on supplemental wages up to $1 million a year, so a two-earner family in a higher bracket usually meets the shortfall in April, sometimes with an underpayment penalty.
Most people come to this when the vests stop being small. Maybe your company went public and a new RSU refresh arrived, while your spouse has a salary, a 403(b) and a separate pay stub. Now there are two W-2s, one 1099-B with odd numbers on it, a quarterly payment date you didn't have last year, and a stock position that grows every vest. Doing it alone stops being simple somewhere around there.
If you're the only earner on the return and each vest is modest, this page probably isn't for you; a later section says what to do instead. Before you read on, have last year's return, a recent pay stub and your vest schedule from the stock plan portal nearby. Examples here are hypothetical and general education, not tax or legal advice.
Is the 22 percent withheld on each vest enough for a two-earner family?
No, not if your household's marginal federal rate is above 22 percent. RSUs count as wages at their vest-day value, and employers withhold the flat 22 percent supplemental rate on them up to $1 million a year, while a joint return taxes the stacked salaries at your real bracket.
Many vesting employees believe the company withholds on every vest, so the tax is handled. The household that gets caught is usually one spouse with large vests at a public company and the other on a salary with a workplace plan, here a teacher's 403(b). Both are in their early 40s, with roughly 14 years before the higher earner wants to stop working. Their combined income lands in a higher bracket than the one the payroll system guesses.
Two more gaps hide in the pay stub. Social Security withholding stops once one employee's wages pass $184,500, the SSA wage base for 2026, so the vest check gets bigger late in the year and you may feel richer than you are. And the 0.9 percent additional Medicare tax is withheld only above $200,000 per employee, while a joint return owes it above $250,000 of combined wages. Two earners at $140,000 each never trigger withholding, yet owe it together.
If your household's marginal federal rate is above 22 percent, set aside the difference on every vest the day it lands: for example, 10 cents per dollar at an assumed 32 percent rate.
RSU vests set the room left for ISOs, the ESPP and the sell-down
Vest income raises your regular tax, and that changes how much ISO spread fits before the alternative minimum tax starts; our ISO exercise planning page works that out. ESPP purchases add more shares of the same ticker on top. Shares sold on vest day carry almost no gain, because basis equals the sale price. That leaves them as the lowest-tax shares to sell first for concentrated stock diversification. So Modera Wealth Management counts all three on one sheet before anyone picks a number to sell.
Is it too early if your vests are under $20,000 annually?
Often, yes. With vests under $20,000 annually and one earner, an extra withholding line on the W-4, selling each vest into a broad index fund and paying at least 110 percent of last year's tax (the IRS safe harbor once AGI is above $150,000) usually covers the bill without a paid engagement. Revisit when vests grow or a second income joins the return.
Raising the 403(b) in November saves two paychecks' worth, not $18,500
Plenty of people treat vests as bonus money, to spend or to leave in the stock. The better use is to let vest cash replace a spouse's paycheck while that spouse defers more salary into a workplace plan.
For illustration: Svetlana (hypothetical), 41, a product director at a chip designer, gets a $50,000 RSU refresh that vests during the year. The couple sells each vest the day it lands, so basis equals the sale price and there's no gain. Pavel, 43, a high-school music teacher, puts $6,000 a year into his 403(b). They use vest cash to replace his take-home pay while he raises his deferral to the $24,500 IRS limit for 2026. That's $18,500 more deferred. At an assumed 32 percent marginal federal rate, the tax bill drops by $18,500 × 0.32 = $5,920, so the real cost is $12,580. Repeated for 14 years at an assumed 5 percent a year, the extra $18,500 annually grows to about $362,600 by the time Svetlana is 55. Fund values can fall, and you can lose part of what you put in.
The first timing error is the calendar. Deferrals must come out of pay during the year, and school payroll often applies a new salary reduction form only from the next month. Waiting until a December vest leaves one paycheck: only about $1,500 of the $18,500 gets deferred, and about $5,400 of that year's $5,920 saving is gone, because deferrals can't be made after year-end.
Two more errors cost money. If a big spring vest lands and nothing goes to the IRS by the June 15 estimated payment date, penalty interest starts running from that date. And if you file with a 1099-B that shows $0 basis on vest-day sales and skip the Form 8949 correction, the same wages get taxed twice.
The worked example
Three timing errors
Thirteen weeks at Modera Wealth Management, from vest calendar to 403(b) change
The first quarter follows a set order. One habit comes straight from our asset location view. Before any vest cash is invested, we write down which account each kind of investment belongs in: broad index funds bought with vest proceeds go in the taxable account, and the extra salary Pavel defers fills his 403(b) up to the $24,500 limit for 2026.
- Weeks one and two: send W-2s, return, vest schedule, pay stubs, 403(b) statement; we compute the withholding gap
- Weeks three to six: playbook arrives with set-aside per vest, any W-4 change, 403(b) form filled in
- Weeks seven to ten: first vest sold, cash routed (bond funds in the 403(b), broad stock funds in taxable)
- Weeks 11 to 13: projected April tax bill checked against the safe harbor; reviews booked before the next vest and at fall open enrollment
Is RSU tax planning worth starting with 14 years to go before you stop working?
Yes, if your vests top $50,000 annually, because the withholding gap and the deferral room both grow with them. Other signs: a spouse's plan sitting below the $24,500 limit, more than $1,000 owed last April (where underpayment penalties can start), or catch-up ages within reach.
The table shows when rules switch on, assuming current-year limits and a family selling vests as they land.
Our limits: RSU tax planning doesn't replace the CPA who files your return, and state tax on vests differs by state; check your state's rules. The next step is the request form, with the vest schedule, both W-2s and last year's return. The work happens mostly over screen-share calls. Modera Wealth Management takes on families with at least $500K in investable assets, and the fee is fixed in a written agreement before anything starts.
| Age | Rule that switches on | What it means for vest cash |
|---|---|---|
| 50 | $8,000 plan catch-up, total $32,500 | Shelter more salary; Roth if wages over $150,000 |
| 55 | Penalty-free 401(k) access after leaving job | Bridge years before 59½ |
| 59½ | No 10% penalty on IRA withdrawals | Vest cash no longer the only bridge |
| 60-63 | $11,250 higher catch-up | Largest deferral years |
| 63 | Income sets Medicare premium at 65 | Lighter vest sales this year |
| 73 or 75 | Required minimum distributions begin | Pre-tax balances get taxed anyway |
Vest cash can replace a spouse's paycheck while that spouse defers more salary.
What people ask about RSU tax planning
I'm the spouse with the 403(b): if I raise my deferral to $24,500, does that lower the tax on my wife's RSU vests?
It lowers the couple's joint tax bill, though not the vests themselves. Deferrals reduce taxable wages on the joint return, so they offset vest income taxed at your shared bracket. Payroll must start the higher deferral early in the year, since contributions can't be made after December 31.
My pay stub shows 22 percent federal withheld on every RSU vest; will we still owe when we file jointly in April?
Probably, if your joint marginal rate is above 22 percent. The flat supplemental rate ignores your other income, so the gap shows up on Form 1040. Check last year's return, add the vest income, and set aside the difference per vest, or raise withholding on a W-4.
Read the rules at the source
How Modera Wealth Management can also help
This is general information, not advice for your specific situation. Investing involves risk, including loss of principal. Nothing here replaces guidance from a tax professional or attorney. Talk to a qualified adviser before you act.