$1,473. That’s what one engineer at a US subsidiary of a Korean electronics company had withheld from a single RSU vest. The Korean parent’s payroll system took a cut. The US subsidiary’s W-2 withholding took another. Neither withholding was a mistake. Both were legal. This is what real RSU double taxation looks like in practice. Two governments took a share of the same income, and that’s not a paperwork error. Unless he filed the right form, he was going to eat both.
Most people who search “RSU double taxation” have a simpler problem. Their 1099-B shows a $0 cost basis. If they don’t fix it, they overpay capital gains tax. They end up paying tax twice on income already taxed once through their W-2. That’s a real issue, and it’s worth understanding first, because it’s the baseline every RSU holder needs to check. But your problem might be different. Say your RSUs are shares of a Korean parent company, such as Samsung, LG, Hyundai, or Coupang. These are granted to you as an employee of the US subsidiary. There’s a second layer that the generic explainer never covers, and it isn’t a paperwork mistake. It’s actual tax withheld by two governments on the same income.
Here’s how to tell which problem you have, and how to fix each one.
The Baseline Case: When RSU Double Taxation Is Just a Cost-Basis Mistake
When RSUs vest at a fully domestic US company, the shares are valued as of the vest date. That value gets added to Box 1 of your W-2 as ordinary income. Say 100 shares vest at $50 each. That’s $5,000 in W-2 income, with federal, state, and FICA withheld through your regular payroll.
Six months later you sell at $60 and get a 1099-B showing $6,000 in proceeds. Sometimes the cost basis field on your 1099-B shows $0, or is blank. That’s common for RSU shares, since brokers often can’t confirm the basis was already taxed. If you accept that number as-is, Schedule D will show a $6,000 gain instead of the correct $1,000. You’d be paying capital gains tax a second time on the $5,000 that was already taxed as income. That’s the classic RSU double taxation complaint, and it’s a reporting error, not real double taxation. The fix is entering the actual cost basis (the vest-date FMV) instead of the $0 your 1099-B shows.
This mechanic — vest-date value equals cost basis — is true no matter whose stock the RSUs represent. It’s the floor everyone needs to get right before anything else applies.
What Changes When RSU Double Taxation Is Real: Korean Parent Company Stock
Say you work for the US arm of a Korean company. Your RSUs are shares of the Korean parent, not a US-listed entity. Two things are different from the start.
First, the grant is priced in KRW on the Korea Exchange, not in USD. Your cost basis in dollars depends on the exchange rate on the exact vest date. It isn’t the day you file your taxes, or the day you sell.
Second, and more importantly, the equity plan is frequently administered out of Korea. That means the Korean parent’s payroll system may withhold Korean tax on the vest value directly. That withholding is separate from whatever the US subsidiary withholds on your W-2. A domestic US company has no equivalent step — there’s no second country’s payroll system anywhere in the chain. This is the structural difference. It isn’t an extra example bolted onto the same article. It’s a second tax authority actually taking money at the same event.
| US-only company RSU | Korean parent company RSU (Samsung, LG, Hyundai, Coupang) | |
|---|---|---|
| Stock priced in | USD | KRW, converted at the vest-date spot rate |
| Who withholds at vest | US subsidiary only (W-2) | US subsidiary (W-2) and possibly the Korean parent’s payroll |
| The usual “double taxation” complaint | A $0 cost-basis entry error on the 1099-B | Can be a real second layer of tax, on top of the cost-basis issue |
| What fixes it | Correct cost basis on Schedule D | Cost basis correction and a Foreign Tax Credit claim for the Korean withholding |
| Extra paperwork | None | Korean withholding certificate (원천징수영수증) from the parent’s payroll |
A Worked Example: KRW Grant, Vest-Date Conversion, Korean Withholding
Say you work at the US subsidiary of a Korean electronics company. 50 RSUs vest on June 1, granted in the parent’s common stock.
- Samsung closing price on the KRX on June 1: ₩72,000 per share
- Total vest value in KRW: 50 × ₩72,000 = ₩3,600,000
- USD/KRW spot rate on June 1 (Federal Reserve H.10): 1,320
- USD vest value: ₩3,600,000 ÷ 1,320 = $2,727
That $2,727 is what should land in Box 1 of your W-2. It’s also your cost basis for a future sale, exactly like the domestic case above.
Now here’s the part that doesn’t happen with a US-only company. The Korean parent’s payroll system also treats this as taxable compensation under Korean law. It withholds Korean income tax before the shares even settle. Assume a 22% effective withholding rate on the KRW-denominated value. ₩3,600,000 × 22% = ₩792,000, or roughly $600 at the same exchange rate.
Meanwhile, the US subsidiary withholds against the same $2,727 through ordinary payroll taxes. Call it $873 combined federal, state, and FICA at a rough 32% marginal rate.
Total withheld on one vest event: $600 in Korea, $873 in the US, on $2,727 of income. That’s real RSU double taxation, not a reporting glitch. It happens whether or not you get the cost-basis number right.
Fixing Real RSU Double Taxation: Form 1116
The tool for this is the Foreign Tax Credit, claimed on Form 1116, not a cost-basis correction. You’re not trying to reduce your income. You’re trying to get a dollar-for-dollar credit against US tax for the Korean tax you already paid.
To claim it, you need documentation from the Korean side. That means a withholding certificate (원천징수영수증), or an equivalent statement from the parent company’s payroll. It should show the KRW amount withheld and the date. Your US subsidiary’s HR or global mobility team can often request this from the parent if it isn’t automatically issued. Convert the withheld amount to USD using the same vest-date rate you used for cost basis. That converted amount becomes your foreign tax paid for Form 1116.
There’s a wrinkle worth flagging honestly. The Foreign Tax Credit limitation is calculated against US tax on foreign-source income. If you worked entirely in the US, the IRS may source 100% of that RSU income as US-source income. That sourcing follows the standard workday-allocation rules. That’s true even though Korea withheld tax on it. Tax treaties often include a mechanism to address exactly this kind of mismatch. But applying it correctly is genuinely technical. So is getting the sourcing and category right on Form 1116 — general limitation versus passive category matters here. This is the point where a CPA with cross-border compensation experience is worth paying for. Get it wrong, and you either leave the credit on the table or claim more than the limitation allows.
If you sell the shares later, that’s a separate calculation from the vest-date issue covered here. The currency conversion and PFIC rules for selling Korean stock walk through the disposal side in full.
Where to Find the Numbers
- Vest-date FMV and share count: your equity platform (Fidelity, Schwab, E*Trade) or your company’s equity/HR team.
- USD/KRW spot rate for the vest date: the Federal Reserve’s H.10 release, not a monthly or annual average.
- Korean withholding amount: the parent company’s payroll or HR system. Ask specifically for a 원천징수영수증, or a written statement of the KRW withheld and the withholding date.
- W-2 Box 1 amount: should already reflect the USD vest value. Check it against your own calculation, since payroll systems sometimes use a different exchange-rate source than the Fed’s.
Keep all four numbers in a spreadsheet per vest date. You’ll need them again when you sell, and again if you ever amend a prior return.
Questions Worth Asking
Does every Korean-parent-company RSU grant get withheld twice?
No. Some Korean multinationals structure their US equity plans so only the US subsidiary withholds. There’s no separate Korean withholding at vest in that case. Whether Korea withholds depends on the specific company’s plan administration and its own tax obligations. Check with your equity or HR team rather than assuming either way.
I already filed without claiming the Foreign Tax Credit for Korean withholding. Can I still get it?
Generally yes, using Form 1040-X. You have three years from the original filing deadline, or two years from payment, whichever is later. You’ll need the Korean withholding documentation for the year in question.
What if I can’t get a withholding certificate from the Korean parent?
Ask HR or global mobility for a written statement of the amount and date, even without the formal certificate. The IRS wants evidence the tax was actually paid. A certificate is the cleanest form of that evidence, but it isn’t the only acceptable one.
Quick Summary
- Most RSU double taxation complaints are actually a cost-basis mistake. Entering $0 instead of the vest-date FMV on your 1099-B causes you to pay capital gains tax twice.
- Korean parent company RSUs (Samsung, LG, Hyundai, Coupang) can carry a second, real layer of RSU double taxation. That happens if the parent’s payroll withholds Korean tax at vest, in addition to your US W-2 withholding.
- The fix for the real version is a Foreign Tax Credit claim on Form 1116, backed by Korean withholding documentation. It isn’t just a cost-basis correction.
This is general information, not a substitute for advice from a CPA or tax attorney. Every situation is a little different, and the rules described here can change without much notice.