How This Calculator Works

The estimator is a screening tool for US citizens who spend the year across several countries. It flags countries where your days may make you tax resident, estimates US federal income tax (which applies wherever you live), flags US states that may still treat you as domiciled, and estimates foreign tax for Hong Kong, Singapore and the UAE from each tax authority's own rates and day rules. For any other country the foreign tax is not estimated, at any number of days, and is left out of the total.

Inputs and Assumptions

Countries and days: Days spent in each country this year. Days not listed are assumed to be spent in the US.
Annual income and income type: Income is attributed to each country in proportion to days spent there. W-2 income is treated as employment income for work done in that country (for a non-local employer), 1099 income as self-employment, and "mixed" as 70% earned and the rest investment income.
State of domicile: The US state you are (or were last) resident in.

Assumptions: you file as single with the basic standard deduction ($16,100 for 2026); the 183-day residency screen is the same for every country (the foreign tax figures use each modelled country's own day rules instead).

Formula

// Residency screen, per country
status = "triggered"  if days ≥ 183
         "warning"    if days ≥ 150
         "safe"       otherwise

attributedIncome = income × days / 365
foreignTax       = countryTax(attributedIncome, kind, days)
                   // the country's own rules (below); null = not estimated

// US federal, 2026 single brackets
usTax = federalTax(max(0, income − $16,100))

// State
daysInUS = 365 − Σ days listed
if state ∈ {CA, NY, NM, SC, VA} and daysInUS < 183:
    flag domicile risk; stateTax = income × stateRate
else if state has income tax and daysInUS ≥ 183:
    stateTax = income × stateRate
stateRate: CA 9.3%, NY 8.5%, NM 5.9%, SC 5.21%, VA 5.75%; other 5%

total = usTax + stateTax + Σ foreignTax (estimated ones only)

// "Stay under 183 days" lever, per country, on the same income
// (what a 183-day stay attributes), so only the day rule differs
below    = countryTax(income × 183 / 365, kind, 182 days)
atOrOver = countryTax(income × 183 / 365, kind, 183 days)
advise staying under only if atOrOver > below, or the country is not modelled

// Country card colour (the dot and bar show status, the day count)
tone = "red"      if days ≥ 183 and (foreignTax > 0 or not estimated)
       "amber"    if 150 ≤ days < 183, unless foreignTax = 0 and atOrOver = 0
       "neutral"  otherwise

The "Stay under 183 days" lever follows those figures. For a country whose rules are not modelled it keeps the usual advice, since many countries treat 183 days as residence. Where the figures show that reaching 183 days costs less (Singapore at ordinary incomes: residents pay progressive rates, non-residents at least 15% on employment income) or makes no difference (Hong Kong employment, the UAE), it says so instead. The red "tax residency triggered" line appears only at 183 days or more where the foreign tax is above zero or not estimated, not under the UAE's $0. The country card is marked the same way: red at 183 days or more only where tax is due or not estimated, amber at 150 to 182 days unless the tax is $0 and stays $0 at 183, and neutral otherwise. The dot and bar show the day count.

Foreign tax

Income is converted from US dollars at the site's static ECB reference rates (2 October 2026), taxed in the local currency, and converted back.

Singapore (IRAS): 183 days or more: resident rates from YA 2024, 0% to 24%. 61 to 182 days: employment income is taxed at 15% or the resident rates, whichever is higher. 60 days or less: short-term employment income is exempt. Foreign-sourced investment income is not taxed. Self-employed income is estimated only at 183 days or more. Personal reliefs and rebates are not deducted. Days are counted per calendar year, and IRAS's administrative concessions are not applied: under the two-year concession, a foreign employee whose employment straddles two calendar years and, with the stay just before and after it, covers a continuous period of at least 183 days is treated as resident in both years (company directors, public entertainers and professionals excluded); under the three-year concession, someone who stays or works in Singapore continuously for three consecutive years is resident in all three, even with under 183 days in the first and third. So a foreign employee with 61 to 182 days in one calendar year can be treated as resident and pay the progressive rates, which is often less than the 15% this calculator charges.
Hong Kong (IRD): a non-Hong Kong employment is exempt when visits total 60 days or less in the year; above that, the income for the days in Hong Kong pays salaries tax for 2026/27: 2% to 17% after the HK$145,000 basic allowance, never more than 15% (16% above HK$5,000,000) of income before allowances. Dividends and interest are not taxed. Self-employed income is estimated only at 183 days or more (the lower of the 7.5% / 15% profits tax and Personal Assessment, which is open to someone in Hong Kong for more than 180 days of the year of assessment). Hong Kong's year of assessment runs from 1 April to 31 March, not the calendar year: the calculator applies the 2026/27 allowances and rates to a calendar year's income, although January to March 2026 falls in 2025/26 (basic allowance HK$132,000, and a 100% tax reduction of up to HK$3,000). PAM 42's 60-day test counts visits per year of assessment too, so 60 days in a calendar year can be more or fewer than 60 in either year of assessment it touches.
United Arab Emirates: no income tax on individuals. A natural person's business income is subject to UAE Corporate Tax when business turnover exceeds AED 1,000,000 in a calendar year (Cabinet Decision No. 49 of 2023); wages and personal investment income are outside it at any amount. Corporate Tax is not modelled, so self-employment income attributed to the UAE above AED 1,000,000 (about $272,300 at the site's rate) is not estimated. Below that line the $0 assumes your business turnover, which can be more than your income, is also under AED 1,000,000.

Data Sources

IRS Revenue Procedure 2025-32 — 2026 federal brackets and standard deduction, via our shared tax data module.
OECD Model Tax Convention, Article 4 — residence and tie-breaker concepts; 183 days is the common domestic-law threshold, used here as a screen.
Singapore — IRAS, Individual income tax rates and Working out my tax residency.
Hong Kong — IRD, Allowances, Deductions and Tax Rate Table (PAM 61), A Guide to Salaries Tax for People Coming to Work in Hong Kong (PAM 42) and A Brief Guide to Taxes Administered by the IRD (2025/26).
United Arab Emirates — u.ae, Taxation; Ministry of Finance, Cabinet Decision No. 49 of 2023 (Article 2): the AED 1,000,000 turnover line for natural persons.
Hong Kong Personal Assessment eligibility — IRD, Guide to Tax Return – Individuals: Personal Assessment (temporary resident: more than 180 days in the year of assessment).
State revenue department guidance (California FTB, New York DTF, Virginia Tax, New Mexico TRD, South Carolina DOR) — the states flagged for domicile risk.
SSA Office of the Chief Actuary — 2026 Social Security wage base of $184,500, quoted in the self-employment tax warning.

Limitations

Double taxation is not netted off. US tax and foreign tax are simply added together. In practice the Foreign Earned Income Exclusion or Foreign Tax Credit usually removes most of the overlap, so the total is an upper bound. IRS Publication 54 explains both.
Foreign tax is estimated only for Hong Kong, Singapore and the UAE. For every other country it is not estimated, at any number of days, and the total leaves it out: many countries tax work done there before 183 days, so assuming zero would understate it and a top rate would overstate it.
A Hong Kong employment (rather than a non-Hong Kong one) is taxed in full whatever the days, and Singapore's 60-day exemption does not cover directors, public entertainers or professionals; neither case is modelled.
Residency is screened on days alone. Many countries also use a permanent home, centre of vital interests, habitual abode or other tests, and some use thresholds other than 183 days or a 12-month rolling window. Treaty tie-breaker rules are not applied.
State tax is a flat assumed rate on gross income, not the state's actual brackets, and the domicile flag is a prompt to get advice, not a determination.
Only single filing status is modelled. Self-employment tax is not added to the total; it is noted in a warning.
Investment income is taxed at ordinary income rates; capital gains and dividend rates are not modelled.

Last Updated

October 2026 — Methodology page published. Federal figures moved to 2026; the self-employment warning now quotes the 2026 wage base ($184,500) instead of the 2024 figure.

14 October 2026 — Foreign tax worked out from each tax authority's own rates and day rules (Singapore, Hong Kong, UAE) instead of income × the country's top rate from 183 days (Singapore, $46,575 attributed: $11,178 shown against $1,502 on the IRAS table). Other countries are no longer given a figure. Status labels now state day counts instead of "Safe".

14 October 2026 (re-audit notes) — The "stay under 183 days" lever now follows the computed figures, so it no longer tells you to stay under 183 days in Singapore, where 183 days or more costs less at ordinary incomes ($85,000: $6,392 at 182 days against $1,225 at 183, on the same income). The "tax residency triggered" line no longer appears under the UAE's $0. UAE self-employment income above AED 1,000,000 is not estimated (Corporate Tax). Hong Kong's April-to-March year and Singapore's administrative concessions are stated.

14 October 2026 (re-check notes) — A country card at 183 days or more is no longer red under a $0 figure (the UAE on wages), and at 150 to 182 days it is no longer amber where the tax is $0 either side of 183 days. Result text names the UAE as "the UAE".

14 October 2026 (follow-up notes) — The formula above now includes the country card's colour rule. "Not included: foreign tax for …" joins two or more countries with "and" ("the Netherlands and Portugal").

Digital Nomad Tax Estimator — Methodology