Restricted Stock vs RSU: Substantive Differences

The core distinction: property now vs. promise later

Restricted stock (also called a restricted stock award, or RSA) is an actual share of company stock transferred to you on the grant date. You own it immediately — your name is on the cap table, you can vote the shares, and you receive dividends. The restriction: if you leave before vesting, the company buys the shares back (usually at the price you paid, which is often zero or near-zero for early-stage grants). The legal framework is IRC § 83(a), which says property transferred in connection with services is taxed at the time it is no longer subject to a substantial risk of forfeiture — i.e., at vesting.

A restricted stock unit (RSU) is a contractual promise: “When you vest, we will deliver one share of stock (or the cash equivalent) per unit.” You own nothing at grant. No shares. No voting rights. No dividends. The company has made you a promise, and that promise converts to actual stock only when the vesting condition is satisfied. RSUs are also governed by IRC § 83, but the taxable event is simpler: you receive the shares at vesting, and their full fair market value at that moment is ordinary income on your W-2.

Side-by-side comparison

The Section 83(b) election: why it only matters for restricted stock

Under IRC § 83(b), you can elect to recognize ordinary income at grant — before the shares vest — on property that is subject to a substantial risk of forfeiture. For restricted stock, this is the single most important tax decision you will make.

The mechanic: you file the 83(b) election with the IRS within 30 calendar days of the grant date. You pay ordinary income tax on the fair market value of the shares at that moment. If the shares are worth $0.10 each and you received 50,000 shares, you recognize $5,000 of ordinary income and pay roughly $1,100–$1,850 in federal tax (depending on your marginal bracket). All future appreciation — from $0.10 to $50, $100, or $500 per share — is taxed as capital gains, and the holding period starts from the grant date.

Without the 83(b) election, you recognize ordinary income at vesting. If those 50,000 shares are worth $25 each when they vest, you have $1,250,000 of ordinary income on your W-2 — taxed at your marginal federal rate (up to 37% in 2026) plus state taxes. That is the difference between $1,850 and $462,500+ in federal tax on the same shares.

RSUs cannot use this election. Since RSUs are not transferred property at grant — they are a promise — there is nothing for IRC § 83(b) to apply to. This is not a loophole or an oversight; it is the structural design of the instrument. RSU holders always pay ordinary income tax at vesting on the full FMV.

Worked example: co-founder RSA vs. engineer RSU

Two employees at the same company, granted equity two years apart. The tax outcomes diverge dramatically.

Maria — co-founder, restricted stock with 83(b)

Maria co-founded a Delaware C-corp in 2022. She received 50,000 restricted shares at $0.10/share (409A valuation), subject to a 4-year vesting schedule. She filed an 83(b) election within 30 days.

James — software engineer, RSUs granted post-Series B

James joined the same company two years later as a senior engineer. He received 4,000 RSUs at a 409A valuation of $12/share, subject to a 4-year vesting schedule with a 1-year cliff.

Maria’s effective federal rate on $2.25M of value: ~23.8%. James’s effective federal rate on $210K of value: ~30.3%. The 83(b) election converted almost all of Maria’s gain from ordinary income (up to 37%) to long-term capital gains (20% + 3.8% NIIT). James had no mechanism to achieve the same result — every dollar of RSU value at vesting is ordinary income by design.

The 83(b) election risk: what happens if the company fails

The 83(b) election is not free money. If Maria’s company had failed and her shares became worthless before vesting completed, she would forfeit the unvested shares — and the $1,200 she paid in tax on the 83(b) income is gone. The IRS does not refund tax paid on an 83(b) election for forfeited shares. She would have a capital loss on the forfeited shares (basis = $5,000, proceeds = $0), but capital losses are limited to $3,000/year against ordinary income under IRC § 1211, so recovering even the basis takes two years of loss deductions.

For early-stage startup employees paying tax on a $0.10/share 83(b), the risk is usually manageable — losing $1,200 is a rounding error against the upside. For later-stage restricted stock at $5 or $10/share, the calculus changes. A 50,000-share grant at $5/share means $250,000 of ordinary income on the 83(b), or roughly $60,000–$92,500 in federal tax at risk if the shares are forfeited.

Where ISOs, NSOs, and ESPPs fit in the picture

RSAs and RSUs are the two main forms of stock-based compensation that deliver shares. But the broader equity compensation landscape includes three other instruments that employees often confuse with RSUs:

Incentive stock options (ISOs) — IRC § 422

ISOs give you the right to buy shares at a fixed exercise price. Unlike RSUs, you pay the exercise price out of pocket. The tax benefit: no ordinary income tax at exercise (but the spread is an AMT preference item under IRC § 56(b)(3)). If you hold the shares 2+ years from grant and 1+ year from exercise, the entire gain qualifies for LTCG rates. The catch: the AMT can create a tax bill at exercise even though you have received no cash, and the 90-day post-termination exercise window under IRC § 422(a)(2) forces a use-it-or-lose-it decision when you leave the company.

Non-qualified stock options (NSOs)

NSOs work like ISOs mechanically — you buy shares at a strike price — but the tax treatment is worse: the spread at exercise is ordinary income on your W-2, immediately. No AMT preference instead of ordinary income. No special holding period requirement. NSOs are more common than ISOs at public companies because they have no $100K annual vesting limit and no employee-eligibility requirements.

Employee stock purchase plans (ESPPs) — IRC § 423

ESPPs let you buy company stock at a discount (typically 15%) through payroll deductions. Qualifying dispositions (held 2+ years from offering date, 1+ year from purchase) get favorable tax treatment on the discount portion. ESPPs are separate from RSUs — most large tech companies offer both, and they stack. If your company offers an ESPP with a lookback provision, the effective discount can reach 30–40% in a rising market.

The 90-day post-termination exercise window for ISOs

This is the rule that catches the most people off guard. Under IRC § 422(a)(2), if you leave your company — voluntarily or through a layoff — your ISOs must be exercised within 90 calendar days of your termination date to retain ISO tax treatment. After day 90, they convert to NSOs, and the spread at exercise becomes ordinary income.

The problem: exercising ISOs requires cash. If you hold 10,000 ISOs with a $5 strike price, exercising costs $50,000 out of pocket — for shares in a company you just left, which may or may not ever be liquid. And the AMT preference on the spread could trigger additional tax. Many employees let ISOs expire because they cannot afford the exercise cost plus the AMT bill, especially during a layoff when cash is tight.

Some companies extend the post-termination exercise window beyond 90 days (to 6 months, 1 year, or even 10 years). But extending past 90 days automatically converts the ISOs to NSOs under IRC § 422(b)(6) — the company is offering a longer window, but the favorable ISO tax treatment is gone.

Concentration risk: the part most people miss

Whether you hold RSAs or RSUs, the post-vesting question is the same: how much of your net worth is tied to one company? Your paycheck, your 401(k) match (sometimes in company stock), your RSUs, your ESPP shares, and your exercised options all point at the same employer. A 40% stock drop does not just reduce your portfolio — it can coincide with layoffs that eliminate the paycheck too.

The framework most advisors use: RSUs at vest are economically equivalent to receiving cash and immediately buying the stock. If you would not take $45,000 in cash and buy 1,000 shares of your employer’s stock at $45/share, you should not hold the RSUs after vesting. The behavioral bias of “I already own it” does not change the concentration math.

For restricted stock with an 83(b) election, the holding-period calculation matters more. Maria needs 12 months from the grant date to qualify for LTCG rates. Selling before that converts her gain from 20% + 3.8% NIIT to her ordinary income rate (potentially 37%). At a $2.25M exit, that is the difference between $535,510 and roughly $832,500 in federal tax — nearly $300,000.

Tender offers and secondary sales: liquidity before IPO

For employees at private companies, vested shares (whether from RSAs or settled RSUs) are often illiquid — you own them, but you cannot sell them on a public exchange. Two mechanisms provide pre-IPO liquidity:

• Company-sponsored tender offers: the company arranges for existing investors or new investors to buy employee shares, usually at the most recent 409A or preferred-round price. These are typically available during specific windows (annually or around funding rounds) and subject to volume limits per employee. Tax treatment: you sold stock, so the gain is capital gains (LTCG if held 12+ months from the date you acquired the shares, which for RSAs with an 83(b) election is the grant date).
• Secondary market sales: platforms like Forge, EquityZen, or Carta CrossMarket match private-company shareholders with buyers. The company’s right of first refusal (ROFR) usually applies, meaning the company can block or match any sale. Tax treatment is the same as a tender offer — capital gains based on holding period and basis.

For RSU holders at private companies, there is a timing wrinkle: many private company RSU plans use a “double trigger” — RSUs vest on the time-based schedule, but shares are not delivered until a liquidity event (IPO, acquisition, or direct listing). Until that second trigger fires, you have vested but unsettled RSUs: you cannot sell because you do not yet own the shares. This means tender offers and secondary sales are typically available only to restricted stock holders or employees who hold exercised options.

Key takeaways

• Restricted stock (RSA) is actual ownership at grant with a forfeiture risk. RSUs are a promise that converts to shares at vesting. The distinction drives everything else — voting rights, dividend treatment, and critically, whether you can file a Section 83(b) election under IRC § 83.
• The 83(b) election is the single largest planning lever in equity compensation. Filing within 30 days of receiving restricted stock lets you recognize ordinary income at the grant-date FMV — potentially $0.10/share for early-stage founders — and convert all future appreciation to long-term capital gains (20% + 3.8% NIIT vs. up to 37% ordinary income). RSU holders cannot use this election.
• RSUs are taxed as ordinary income at vesting, with the full FMV hitting your W-2. Employers typically withhold at the 22% supplemental flat rate, which under-withholds for employees in the 32%+ bracket (single taxable income above $197,300 in 2026). Plan for an April 15 true-up.
• ISOs under IRC § 422 have a 90-day post-termination exercise window that converts them to NSOs if missed. The AMT preference on the exercise spread can create a tax bill with no corresponding cash. These are different instruments from RSAs and RSUs but frequently appear in the same compensation package.
• Post-vesting, the concentration question is the same for both instruments: holding company stock by default is not a strategy. If you would not buy the stock with new cash today, the tax-efficient move is usually to sell at vest and diversify — especially when your paycheck, 401(k) match, and career trajectory already depend on the same company.