RSUs vs. Stock Options: Which Is Better for Software Engineers?

You just got two offers. One from a public company paying $400K total comp, heavy on Restricted Stock Units (RSUs). One from a Series C startup offering a lower base plus 50,000 Incentive Stock Options (ISOs) at a $2 strike price. Your friends have opinions. Blind has opinions. Your recruiter is "just checking in." And you still don't know which one actually puts more money in your pocket.

This is the equity question that trips up more software engineers than any technical interview. Not because the math is hard, but because nobody explains the rules until you've already made the decision.

Here's how RSUs and stock options actually work, how they're taxed, and which one is better depending on where you are in your career.

How RSUs Work

An RSU is a promise. Your employer says: "We'll give you X shares of company stock after you've stayed long enough." You don't pay anything for them. You don't buy them. They just show up in your brokerage account once they vest.

The key mechanics:

• No cost to you. RSUs have no strike price, no purchase requirement. When they vest, you own the shares.
• Vesting schedule. Most big tech companies use a four-year vesting period. Google front-loads theirs (roughly 33/33/22/12 over four years). Amazon back-loads theirs (5/15/40/40). Meta vests quarterly with no cliff. Microsoft and Apple split evenly at 25% per year.
• Value is tied to stock price. If the stock goes up, your RSUs are worth more. If it drops, they're worth less. But they're never worth zero unless the stock itself hits zero.
• Taxed at vest. This is the part that surprises people. The moment your RSUs vest, the full market value counts as ordinary income. Federal tax, state tax, Social Security, Medicare. Your company withholds a portion automatically, usually by selling some of the shares.

RSUs are the standard equity vehicle at public companies. If you're at Google, Meta, Amazon, Microsoft, Apple, or any large public tech company, your equity is almost certainly RSUs. As you move up in level, RSUs become the dominant piece of your total compensation. At senior and staff levels, equity can represent 50-70% of your total comp.

How Stock Options Work

A stock option gives you the right to buy company shares at a fixed price (the "strike price") during a set window. The bet is that the company's stock will be worth more than your strike price by the time you exercise.

There are two types, and the difference matters for your taxes.

ISOs (Incentive Stock Options)

• Available only to employees. Contractors and advisors can't get these.
• No tax at exercise (usually). If you exercise ISOs and hold the shares, you don't owe ordinary income tax on the spread. You might owe Alternative Minimum Tax (AMT), though. More on that below.
• Favorable capital gains treatment. If you hold the shares for at least one year after exercise and two years after the grant date, you pay long-term capital gains rates on the profit. That's 15-20% instead of the 37%+ you'd pay on ordinary income.
• $100K annual limit. Only $100K worth of ISOs (based on the strike price) can become exercisable in any calendar year.

NSOs (Non-Qualified Stock Options)

• Available to anyone. Employees, contractors, advisors, board members.
• Taxed at exercise. The spread between your strike price and the current fair market value counts as ordinary income the moment you exercise. Payroll taxes apply too.
• No AMT risk. The tax treatment is straightforward but less favorable.

The AMT Trap

This is where ISOs get dangerous. The Alternative Minimum Tax (AMT) is a parallel tax system. When you exercise ISOs, the spread between your strike price and the fair market value counts as income under AMT rules, even if you haven't sold a single share.

Here's what that looks like in practice. Say you have 100,000 ISOs at a $1 strike price. The company's current fair market value is $5 per share. You exercise all of them. Under regular tax rules, you owe nothing. Under AMT rules, you just recognized $400,000 in income. You could owe six figures in taxes on shares you can't even sell yet if the company is still private.

This has wiped out engineers financially. It happened during the dot-com bust, and it still happens today when people exercise options in highly valued private companies, then the valuation drops before they can sell.

RSUs vs. Options: The Real Comparison

The right choice depends on one thing: the stage of the company you're joining.

Public Company (Big Tech)

RSUs win. Not close.

• No risk of going to zero. Google stock might drop 20%, but it won't vanish.
• No exercise decision. You don't have to time anything or come up with cash.
• No AMT exposure. Taxes are simple. Shares vest, you sell or hold, done.
• Predictable value. You can calculate what your RSU grant is worth today. With options, you're guessing.

Every major public tech company uses RSUs for a reason. They're cleaner, lower-risk, and easier to plan around. When you get promoted at a public company, your equity refresh grant will also be RSUs, layered on top of your initial grant.

Pre-IPO Startup (Series A through Late Stage)

Options are the only real choice here, because startups almost always grant ISOs or NSOs. And options can be worth dramatically more than RSUs if the company succeeds.

The upside case: You join at a $50M valuation with a $0.50 strike price. The company goes public at a $5B valuation. Your shares are now worth 100x what you paid. The tax treatment on ISOs means you might pay 15-20% capital gains instead of 37% income tax. That difference alone can be worth hundreds of thousands of dollars.

The downside case: The company never goes public. Or it goes public below your strike price. Or it gets acquired for less than the last round's valuation. Your options expire worthless. The base salary you took a cut on doesn't come back.

The honest math: Most startups fail or return less than their last private valuation. Options at a startup are a calculated bet, not a compensation plan. Treat them that way.

Late-Stage Pre-IPO (Series D+, Likely to IPO)

This is the gray zone. Some late-stage companies offer RSUs that vest on a "double trigger" (time-based vesting plus a liquidity event like an IPO). Others still offer options.

If you're comparing a late-stage offer with RSUs to a public company offer with RSUs, the calculus is simpler. The main risk is timing. You can't sell double-trigger RSUs until the company goes public or gets acquired. That could be six months or three years. Your comp is real, but it's illiquid.

Tax Comparison at a Glance

Factor	RSUs	ISOs	NSOs
Cost to you	$0	Strike price at exercise	Strike price at exercise
Taxed when	At vesting	At sale (if qualifying)	At exercise
Tax type	Ordinary income	Long-term capital gains (if held)	Ordinary income on spread
AMT risk	None	Yes, on exercise spread	None
Payroll tax	Yes, at vest	No (at exercise)	Yes, at exercise
Risk of $0 value	Very low (public co.)	High (startup)	High (startup)

The 2026 tax wrinkle. The Tax Cuts and Jobs Act provisions are set to change. If the top marginal rate reverts from 37% to 39.6%, the ordinary income tax hit on RSU vesting and NSO exercise gets larger. This makes the long-term capital gains treatment on ISOs relatively more valuable. Talk to a tax advisor about timing if you're sitting on unexercised options.

Five Mistakes Engineers Make With Equity

Treating RSUs like a bonus. RSUs vest and hit your account, so many engineers spend them immediately or ignore them. But RSUs are a major part of your comp. At senior levels, they can be $200K-$400K per year. Treat them like the compensation they are, with a real plan for selling, holding, or diversifying.

Holding too much company stock. You already depend on your employer for your paycheck, your benefits, and your career growth. Holding all your vested RSUs on top of that means your financial life is completely tied to one company's stock price. Concentration risk is real. Diversify.

Not understanding your vesting schedule. Amazon's back-loaded schedule means your Year 1 and Year 2 cash flow looks very different from Year 3 and Year 4. Google's front-loaded schedule means your comp drops in years 3-4 unless you get strong equity refreshers. Know what you're getting and when.

Exercising ISOs without checking AMT. Before you exercise options, calculate your potential AMT liability. This is not optional. Use a tax calculator or talk to a CPA. The engineers who get burned are the ones who exercise first and check the tax bill later.

Ignoring the exercise window. Most companies give you 90 days to exercise vested options after you leave. Some give you longer. If you don't exercise within the window, your vested options disappear. If you're thinking about leaving a startup, check your option agreement first. The exercise cost plus potential tax bill might change your timeline.

Which One Should You Pick?

There's no universal answer. But here's a framework.

Choose the RSU offer if:

• You want predictable, low-risk compensation
• You're joining a public company or late-stage pre-IPO
• You don't want to deal with exercise decisions or AMT
• You value liquidity (you can sell RSUs the day they vest)
• You're at a career stage where stable comp matters (mortgage, family, paying down debt)

Choose the option offer if:

• You're early-career and can absorb financial risk
• The startup has strong fundamentals and a credible path to IPO or acquisition
• The strike price is very low relative to projected growth
• You have savings to cover the exercise cost and potential AMT
• You understand that options could be worth nothing

The hybrid approach. Some engineers work at a public company, stack RSUs, and invest a portion of that liquid comp into startup angel investments or their own side projects. This gives you the stability of RSU income with startup-like upside on the side, without gambling your primary compensation.

How Equity Fits Into Your Promotion Strategy

Equity isn't just about the grant you got when you joined. It's part of your total comp trajectory, and it changes every time you level up or negotiate a promotion raise.

At junior levels (L3/L4 at Google, E3/E4 at Meta), base salary is the biggest piece. Equity might be 20-30% of total comp. By the time you hit senior (L5/E5), equity is often 40-50%. At staff and above, it can be the majority.

This means your promotion case is also a compensation case. Every level you gain doesn't just change your title. It changes the size of your equity grants, the size of your annual refreshers, and the compounding effect of stock price appreciation on a larger share count.

The engineers who understand this build their promotion evidence with total comp in mind. They document their impact, track their wins, and make their case with the full picture.

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CareerClimb helps you track your compensation growth alongside your promotion case. Your equity, your wins, your plan, all in one place. Download CareerClimb and start building your case today.