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Equity & Stock Options Tax Hub 2026: RSU & ISO Guide

Daniel · CountryTaxCalc Updated June 2026
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KEY INSIGHT
RSUs are taxed as ordinary income when they vest — the fair market value on vest date is treated as wages. Stock options (ISOs) have preferential treatment if held correctly, but trigger AMT risk. For expats, equity income sourced across multiple countries can be taxable in each jurisdiction proportionally. Use the guides below for your equity type and situation.
At a glance

Key Facts

RSUs: Income at Vest, Capital Gains at Sale
Restricted Stock Units (RSUs) are taxed in two stages: (1) at vesting — the fair market value of the shares on the vest date is ordinary income, subject to income tax and FICA withholding; (2) at sale — any subsequent gain above the vest-date value is a capital gain (long-term if held over one year, short-term if sold within one year of vesting). Many employees who sell immediately after vesting have minimal or no capital gains event — only the ordinary income event at vest.
ISO vs NSO: The Key Distinction
Incentive Stock Options (ISOs) receive preferential tax treatment: no ordinary income tax at exercise (though Alternative Minimum Tax may apply), and if held for the required period (2 years from grant, 1 year from exercise), gains are taxed at long-term capital gains rates. Non-Qualified Stock Options (NSOs / NQSOs) are taxed as ordinary income at the spread (difference between exercise price and FMV) on the date of exercise. ISOs are only available to employees; NSOs can be issued to contractors and directors.
The Withholding Gap Problem
Most employers withhold a flat 22% (or 37% for supplemental wages above $1 million) on RSU income at vest — but your actual marginal rate may be significantly higher once all income is combined. If your total income puts you in a higher bracket, the flat withholding understates your actual tax liability, creating an underpayment that must be addressed via estimated tax payments or at filing. This is the most common tax error for high-earning RSU recipients.
Multi-Country Equity Apportionment
For expats and internationally mobile employees who worked in multiple countries during a vesting period, equity income must typically be apportioned between countries based on working days. Each country's share of the equity income is taxable in that country. This creates a multi-filing obligation — income reported in country A, reported again (with foreign tax credits) in country B, and potentially reported in the US for American employees. The RSU Tax for US Expats guide covers this apportionment calculation in detail.
Introduction

Equity compensation — RSUs, stock options, ISOs, NSOs, ESPPs, and performance shares — is one of the most complex areas of personal tax planning, particularly for technology workers, executives, and internationally mobile employees. Vesting, exercise, and sale events each trigger different tax consequences. Multi-country employment complicates matters further: equity earned while working in multiple jurisdictions may be taxable in each country proportionally.

This hub collects every equity and stock option tax guide on CountryTaxCalc, organised by compensation type and situation. All figures are sourced from official IRS, state, and international tax authority publications.

Section 01

RSU Tax Guides

Restricted Stock Units are the most common form of equity compensation for tech workers. These guides cover every aspect of RSU taxation:

Section 02

Stock Options: ISO, NSO & Comparison

Stock options have different tax treatment depending on their type and how they are exercised and held:

Section 03

Advanced Equity: Angel Investing & QSBS

For founders, investors, and employees at early-stage companies, the Qualified Small Business Stock (QSBS) exclusion under Section 1202 is one of the largest tax breaks available in the US — potentially excluding up to $10 million (or 10x the adjusted basis) in capital gains from federal tax entirely:

Section 04

Related Hubs

Equity compensation tax planning connects with these broader topics:

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FAQ

Frequently Asked Questions

How are RSUs taxed?

RSUs (Restricted Stock Units) are taxed as ordinary income at the time of vesting. The fair market value of the shares on the vest date is treated as compensation and is subject to federal income tax, state income tax, Social Security, and Medicare (FICA) withholding — just like salary. Your employer will typically withhold a flat supplemental rate (22% federal, or 37% if your total supplemental wages exceed $1 million). If your effective tax rate is higher than the withholding rate, you owe the difference. After vesting, if you hold the shares and they appreciate further before you sell, the gain above the vest-day price is a capital gain — long-term (0–20%) if held over one year, short-term (ordinary income rates) if sold within one year.

What is the difference between ISOs and NSOs?

Incentive Stock Options (ISOs) receive preferential tax treatment: there is no ordinary income tax when you exercise them (though the spread may trigger the Alternative Minimum Tax). If you hold the shares for at least 2 years from grant date and 1 year from exercise date, the entire gain is taxed at long-term capital gains rates. Non-Qualified Stock Options (NSOs) are taxed as ordinary income at exercise — the spread between the exercise price and the fair market value on exercise date is treated as compensation. ISOs can only be granted to employees; NSOs can be granted to contractors and non-employee directors. ISOs cannot be exercised after leaving the company (typically 90 days grace period).

What is an 83(b) election and when should I make it?

An 83(b) election allows you to pay income tax on unvested equity at the current value rather than at the value when the equity vests. If the company's stock is worth very little now (early startup stage) but you expect it to be worth much more when it vests, an 83(b) election means you pay income tax on the low current value — converting all future appreciation into capital gains taxed at preferential rates. The election must be made within 30 days of the initial grant — no exceptions. If the company fails or you leave before vesting, you cannot recover the tax paid on unvested shares. An 83(b) election is generally beneficial for founders and early employees at high-growth startups.

How is equity compensation taxed for international employees?

Equity income earned while working in multiple countries is typically subject to taxation in each country proportionally. The portion of equity income attributable to services performed in each country during the vesting period is taxable in that country. This is called 'apportionment' and is based on working days. For example, if you vested 1,000 shares and worked 60% of the vesting period in the US and 40% in the UK, approximately 60% of the income is US-sourced and 40% is UK-sourced. The RSU Tax for US Expats and International Workers guide covers the mechanics of this calculation, plus the foreign tax credit rules that prevent double taxation.

What is the Alternative Minimum Tax (AMT) and how does it affect ISOs?

The Alternative Minimum Tax (AMT) is a parallel tax system with fewer deductions that applies if it would result in a higher tax than the regular tax. For ISO holders, the spread between the exercise price and the FMV at exercise — which is not taxed under regular income tax — is an AMT preference item. This means exercising ISOs can trigger significant AMT liability even though no regular income tax is due at exercise. Planning ISO exercises carefully — particularly the timing and amounts — is essential to manage AMT exposure. The AMT exemption for 2024 is $85,700 (single) / $133,300 (married), phased out above $609,350 / $1,218,700.

Should I sell my RSUs immediately when they vest?

The decision depends on whether you want concentrated exposure to your employer's stock. From a tax perspective, there is no tax benefit to holding RSUs after vesting — the vesting event is already taxable as ordinary income regardless of whether you sell. Holding creates risk of subsequent share price decline on a position you've already been taxed on. Many financial advisers suggest selling RSUs promptly after vesting (or applying tax-withholding shares) to diversify and avoid the concentration risk. If you hold for over a year after vesting, any additional gain qualifies for long-term capital gains rates — which is the only tax upside from holding rather than selling immediately.
Disclaimer:Equity compensation tax rules — including AMT thresholds, FICA rates, and state withholding rules — change annually. All figures in the linked guides are sourced from official IRS, state revenue authority, and international tax publications and are reviewed at the date shown. This hub provides general educational information only — not tax or financial advice. Equity compensation planning for significant grants, multi-country vesting, or AMT exposure should involve a qualified tax adviser or CPA with equity compensation experience.
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