by David Jarmusz

A prospective client came to us recently with a problem: When her Restricted Stock Units (RSUs) vested last spring, she received only 560 of her 1,000 shares. The other 440 had been withheld to cover taxes. Even so, she still owed an additional $16,000 when she filed because automatic withholding hadn’t covered her full tax liability. She was not at all pleased with the surprise tax bill and was disappointed that her current preparers had failed to mitigate it.

Her situation is common. RSUs are taxed as ordinary income at vesting, before you receive any cash. Default withholding is calculated at a flat supplemental rate that frequently falls short of an individual’s true marginal rate, particularly for high earners in states like New York and California with significant income taxes. The timing of vesting also matters: a large grant vesting in a high-income year can push taxable income into a higher bracket than anticipated.

RSUs are among the most widely offered forms of equity compensation at publicly traded companies across industries, from technology and financial services to healthcare and consumer brands. This guide explains how they are taxed, how withholding works, what happens after vesting, and how RSU decisions can be integrated into a broader wealth plan.

How RSUs Work

RSUs represent a promise by your employer to deliver company shares (or sometimes their cash equivalent) once specified vesting conditions are met. Until vesting occurs, you generally do not own the shares and typically have no voting rights.

Upon vesting, shares are delivered to you, and the fair market value of those shares becomes taxable compensation. The tax event occurs at that moment, not at grant, and not when you eventually sell.

Grant, Vest, and Sale: Three Distinct Events

Understanding the distinction between these three events is essential to managing RSU taxes effectively.

1. Grant date: Your employer promises future shares. No tax is due. The shares are unvested and generally forfeitable if you leave before the vesting date.
2. Vesting date: The critical tax event. The fair market value of shares at settlement (typically the same day as vesting, but not always) is included in your W-2 as ordinary income. Your employer withholds taxes at settlement, typically by withholding a portion of the shares, a process called net settlement or sell-to-cover.
3. Sale date: When you sell the shares you received, any change in value since the vesting date is treated as a capital gain or loss, short-term or long-term, depending on how long you held the shares after vesting.

Many people are surprised to learn that the vesting event triggers immediate tax liability, whether or not they sell the shares. You owe tax on the full fair market value at vesting, regardless of what you do with the shares afterward.

How RSUs Are Taxed at Vesting

RSUs are taxed as ordinary income upon vesting under IRS Section 83. The fair market value of the shares at settlement, which is typically the vesting date, but may differ if settlement is delayed, is included in taxable wages and reported in Box 1 of your Form W-2. The IRS discusses the treatment of compensation income in IRS Publication 525: Taxable and Nontaxable Income.

Because RSU income is treated as wages, it is subject to:

• Federal income tax at your marginal rate
• Social Security tax, up to the annual wage base
• Medicare tax on all wages
• The Additional Medicare Tax for higher-income earners
• State income tax, which varies significantly by location

For high earners in high-tax states, the combined rate on RSU income can reach 45–50% of vest-date value. This is frequently higher than employees expect, particularly those who have not previously held equity compensation.

The Withholding Gap

Employers are required to withhold taxes when RSUs vest, typically by withholding shares rather than requiring an out-of-pocket payment. RSU income is treated as supplemental wages for withholding purposes.

The federal supplemental withholding rate is a flat percentage that applies to supplemental wages below a threshold set by the IRS; amounts above that threshold are subject to the top marginal rate. For many high earners, the flat rate falls well below their actual marginal rate after federal, state, and local taxes are taken into account. The result is a withholding gap. Taxes withheld at vesting are insufficient to cover the full liability, and the shortfall must be addressed through estimated tax payments or W-4 adjustments.

This gap is one of the most common and costly surprises for employees receiving RSUs for the first time. Identifying and closing it before year-end is one of the most valuable planning steps you and your advisor can take.

What Happens After Vesting

Once RSUs vest and shares are delivered, you own the stock outright. Any subsequent change in value is treated as a capital gain or loss when the shares are sold. Your holding period for capital gains purposes begins on the vesting date.

If you sell shares immediately upon vesting, capital gain or loss is typically negligible; the sale price is close to the value already taxed as wages. If you hold shares, future appreciation is taxed as a short-term capital gain (at ordinary income rates) if sold within one year of vesting, or as a long-term capital gain (at preferential rates) if held for more than one year.

The decision to hold or sell is therefore not primarily a tax decision; it is an investment decision, with tax consequences that follow.

Sell or Hold: Concentration Risk and Portfolio Design

After vesting, holding RSU shares means making an active choice to maintain or increase exposure to a single stock. For employees whose income, career trajectory, unvested equity, and retirement savings are already linked to their employer’s performance, that concentration can be substantial, even before accounting for the current vest.

A structured framework, such as systematically selling a portion of vested shares and reinvesting into a diversified allocation, can help align employer equity exposure with long-term portfolio targets. In some cases, partial retention may be appropriate when conviction is high and concentration is modest. In others, disciplined diversification better serves long-term financial objectives.

From a pure tax standpoint, there is no advantage to holding RSUs for less than twelve months after vesting. You have already paid ordinary income tax on the full vest-date value. Any short-term appreciation will be taxed at ordinary income rates as well. The potential tax benefit of holding only materializes after twelve months, when long-term capital gains rates apply to appreciation above the vest-date value.

That potential benefit must be weighed honestly against the market risk of holding a concentrated single-stock position, often in the same company that employs you.

State Income Tax on RSUs

State income tax can add materially to the total tax cost of RSU vesting, and the rules are more complex than they may appear.

States tax RSU compensation based on where you physically performed work during the vesting period, generally measured from the grant date to the vest date, not based on where you live at the time of vesting or where your employer is headquartered. For employees who have lived or worked in multiple states over the course of a multi-year vesting schedule, income may be allocated across several states, each potentially requiring a separate tax return.

Relocation and Timing Considerations

For employees considering a relocation, particularly to states without income tax, the timing of a move relative to vesting events can have significant financial consequences. Income sourcing rules mean that moving states does not automatically eliminate tax liability on unvested grants that accrued during prior residency in a higher-tax state.

Strategic domicile planning around large vesting events, IPO lockup expirations, or significant equity refreshes can be meaningful, but it requires careful analysis of each state’s sourcing rules and documentation requirements. This is an area where professional guidance is particularly important, as the rules vary materially by state and the consequences of errors can be costly.

Estimated Tax Payments and the Withholding Gap

When withholding falls short of actual tax liability, employees must make quarterly estimated tax payments to avoid underpayment penalties.

Safe Harbor Rules

Two safe harbor thresholds protect against underpayment penalties. You are generally protected if your total withholding and estimated payments equal at least 90% of your current year tax liability, or 100% of your prior year tax liability (110% if your adjusted gross income exceeded $150,000 in the prior year). Meeting either threshold prevents penalties even if a balance remains due at filing.

One important nuance: tax withheld by your employer is treated as paid evenly throughout the year, regardless of when it was actually withheld. This means that increasing W-4 withholding late in the year (requesting a specific additional dollar amount per paycheck, for example) can retroactively reduce underpayment exposure for the full year. This is often a more practical solution than making a lump-sum estimated payment in the fourth quarter.

Coordinating Estimated Payments With Vesting Events

For employees with uneven vesting schedules or large one-time grants, the annualized income installment method (IRS Form 2210) allows estimated payments to be sized to the income actually earned in each quarter rather than spread evenly across the year. This can prevent overpayment in early quarters when income is lower.

Proactive mid-year modeling—projecting total vesting income, calculating the expected shortfall, and determining the most efficient way to close it—is one of the most concrete and immediate ways RSU planning can add value.

Year-End Planning and Cash Flow Coordination

Large RSU vesting events can materially increase annual taxable income, creating both a tax challenge and a planning opportunity. Several strategies can improve outcomes when coordinated thoughtfully before December 31.

Retirement Contributions

Contributions to tax-advantaged retirement accounts reduce taxable income dollar-for-dollar up to annual limits. For employees with access to a 401(k), maximizing contributions in high-vest years is one of the most straightforward ways to reduce the marginal tax cost of RSU income. Employees with self-employment income may have access to additional vehicles (e.g., Solo 401(k) or SEP-IRA) that further expand deferral capacity.

The backdoor Roth IRA and, where plan provisions permit, the mega backdoor Roth strategy can also be valuable complements to RSU planning for high earners who exceed direct Roth contribution income limits.

Charitable Giving

Donating appreciated RSU shares held for more than one year directly to a qualified charity or donor-advised fund may allow the donor to deduct the full fair market value while avoiding capital gains tax on appreciation since vesting. In high-interest years when income and, therefore, the marginal tax rate are elevated, the value of charitable deductions is at its highest. Bunching multiple years of charitable giving into a single high-income year can amplify this benefit.

Tax-Loss Harvesting

Capital losses elsewhere in the portfolio can offset capital gains and, subject to annual limits, a portion of ordinary income. In years with significant RSU vesting, a systematic review of the portfolio for harvesting opportunities, coordinated with wash-sale rules, can reduce overall tax liability.

Medicare Premium Implications

Significant increases in modified adjusted gross income can trigger Medicare premium surcharges (IRMAA) two years later. The Social Security Administration publishes current Medicare premium thresholds annually. If you’re approaching retirement or already enrolled in Medicare, RSU vesting projections should explicitly incorporate these thresholds.

RSU Tax Reporting Basics

RSU tax reporting involves multiple forms that must be reconciled carefully to avoid errors and to prevent income that was already taxed as wages from being taxed again as a capital gain.

At vesting, RSU income is reported in Box 1 of Form W-2. At sale, the brokerage reports the proceeds on Form 1099-B. The cost basis shown on Form 1099-B (the value already taxed as ordinary income at vesting) must be confirmed and, if necessary, adjusted before reporting the sale on Schedule D. Using an unadjusted or incorrect basis is one of the most common RSU filing errors, and it results in double taxation of the compensation element.

Employees who participated in equity plans administered through a third-party platform will typically receive supplemental statements from the plan administrator showing vest-date fair market values for each tranche. Retaining these records is essential, particularly for employees with multiple vesting events across several years or across multiple states.

Common RSU Planning Pitfalls

Most RSU planning mistakes are not due to misunderstandings of the tax code. Instead, they are about failing to act on it proactively. The most common errors include:

• Assuming employer withholding covers the full tax liability
• Failing to make estimated tax payments when a withholding gap exists
• Allowing employer stock to accumulate across vesting events without a systematic diversification framework
• Failing to adjust the cost basis at sale, resulting in double taxation
• Overlooking state tax sourcing rules when relocating
• Missing the opportunity to coordinate vesting events with retirement contributions, charitable giving, or other year-end planning strategies

Each of these is addressable with timely planning. Failing to address them can result in a significant, unnecessary tax bill, penalties, and concentrated risk.

How Lido Advisors Approaches RSU Planning

At Lido Advisors, RSU planning is integrated into a year-round wealth management process rather than a once-a-year tax-preparation exercise. We recognize that RSU taxation creates both challenges and opportunities, and that the most valuable planning happens before vesting events, not after.

Our approach coordinates vesting schedules with estimated tax projections, retirement contribution strategy, charitable giving plans, and portfolio construction. For clients with complex equity compensation, including RSUs alongside stock options, ESPPs, or deferred compensation, we model the interaction across vehicles to ensure that decisions made in one area do not create unintended consequences in another.

We also work with clients on employer stock concentration, helping to design systematic diversification frameworks that aim to reduce single-stock exposure over time in a tax-aware manner.