The part nobody escapes: citizenship-based taxation
The United States is the only major economy that taxes by citizenship rather than residence. However long you live in Valencia, you keep filing a federal return (Form 1040), an FBAR for foreign accounts over $10,000, and — above higher thresholds — FATCA Form 8938. Spain, meanwhile, will require its own foreign-asset declaration, form 720, pointing the other way. The double paperwork is unavoidable; double payment usually is not.
Two tools prevent it. The foreign tax credit (Form 1116) offsets US federal tax dollar-for-dollar with Spanish tax paid — and since Spanish rates generally exceed US federal rates at the same income, the credit typically zeroes the federal bill and banks the surplus for future years. The alternative, the foreign earned income exclusion (around $130,000, indexed annually), simply removes earned income from the US base. In high-tax Spain the credit usually wins; the exclusion regains the advantage for Beckham-regime users whose flat 24% Spanish rate can dip below their would-be US bracket. Model both before electing — revoking the FEIE locks you out of it for five years.
Two American quirks survive every strategy: the 3.8% net investment income tax cannot be offset with foreign tax credits (and retirement accounts have their own map), and US-source investment income keeps its US taxation with Spain granting the relief instead, under the 1990 treaty and its 2019 protocol.
The part that depends on your state: three kinds of goodbye
State income tax is where otherwise identical moves diverge by five figures. States fall into three families:
| Family | States (examples) | What leaving looks like |
|---|
| No income tax | Florida, Texas, Washington, Nevada, Tennessee, South Dakota, Wyoming, Alaska, New Hampshire | Clean exit. Nothing to sever; many nomads deliberately establish domicile here first. |
| Standard | Most others (New York, Illinois, Colorado…) | Release you once you establish a genuine foreign home; part-year return in the exit year. New York still audits high earners' exits aggressively — keep evidence. |
| "Sticky" | California, Virginia, South Carolina, New Mexico | Presume you are still theirs until proven otherwise. Domicile survives the flight ticket: licenses, voter registration, property, even gym memberships are counted as ties. |
California deserves its reputation. With a top rate above 13% and no credit for foreign taxes paid, a Californian who moves to Madrid without severing domicile can owe Sacramento on income Spain already taxed — the worst legal outcome available. Its only statutory escape, the safe-harbor rule, requires an employment contract keeping you abroad for over 546 days, and it does not cover the self-employed. The practical playbook, done before departure: close the ties Sacramento counts, document a new domicile (often a no-tax state, using family or a mail-forwarding address), then leave. Order matters; doing it from a Spanish café is years harder.
The Spanish side: visa, Beckham and the Social Security question
Spain's digital nomad visa (startup law) admits remote employees and, with conditions, freelancers with foreign clients. Remote employees of a US company can usually opt into the Beckham regime — 24% flat up to €600,000 for six years, most non-Spanish income excluded, and exemption from form 720 — within six months of registering with Social Security. The crossover salary below which the ordinary regime beats the flat rate sits around €54,000–66,000 depending on the region.
Social Security is governed by the US–Spain totalization agreement, and it decides more money than most nomads expect. Employees temporarily posted or kept on a US payroll can remain under US Social Security with a certificate of coverage (typically up to five years), paying no Spanish contributions; without it, Spanish rules apply. The self-employed generally owe contributions in the country where they work — meaning Spanish autónomo quotas instead of the 15.3% US self-employment tax, never both. Which side is cheaper depends on income: Spanish quotas are bracketed (≈€206–607/month in 2026) while the US takes a flat percentage — above roughly $50,000 of profit, the Spanish side is usually the lighter one.
The analysis
For Americans, the Spain decision is rarely about Spanish rates — it is about sequencing three systems so their reliefs actually connect. The same $120,000 remote salary can produce radically different outcomes: a Floridian employee under Beckham with a certificate of coverage keeps close to Singaporean levels of net pay; a Californian freelancer who left domicile unresolved can face Spanish progressive rates plus a Sacramento bill on top, with no credit bridging them. Neither outcome is luck. Both were decided before the plane took off.
The honest summary for the planning spreadsheet: the IRS obligation is permanent but usually costless beyond compliance; the state obligation is optional but only if handled before departure; and the Spanish obligation is the largest number yet the most controllable one, thanks to the Beckham election and the regional spread this site's calculator quantifies. Plan in that order — state, timing, Beckham — and the three-headed problem becomes an ordinary, if paperwork-heavy, European relocation.
General information under 2026 rules — not tax, legal or immigration advice. US federal, state and treaty outcomes depend heavily on individual facts; the FEIE figure is indexed annually and state rules change. Verify with a cross-border professional before relying on any figure here.