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Every article links to the relevant European Union, US, UK, or Canadian official source. The guides explain arithmetic and source boundaries, not an individual's eligibility or final legal or tax position.
Schengen 90/180
6 minute read
The Schengen 90/180 rule, without the calendar shorthand
Understand what “90 days in any 180-day period” asks you to check, why it is a shared Schengen allowance, and where a calculator stops being authoritative.
5 minute read
How to count Schengen entry and exit days correctly
Count both boundary dates, handle same-day visits and overnight travel, and turn passport stamps into date ranges that can be checked consistently.
6 minute read
How the rolling 180-day Schengen window moves
See why the reference period has no universal reset day, how older travel expires one date at a time, and how to inspect the window behind a result.
6 minute read
A worked 90/180 example with several Schengen stays
Follow three separate visits through a rolling-window check and see why exact ranges are more useful than a single total of days used.
6 minute read
How to plan a future Schengen trip against the 90/180 rule
Turn a tentative itinerary into a daily compliance check without mixing planned travel into the completed ledger or treating a calculator as border approval.
7 minute read
Eight common mistakes in Schengen day calculations
Avoid fixed-window resets, exclusive exit dates, country-by-country allowances, merged absences, and other errors that produce a convincing but unsafe result.
6 minute read
How to compare Roam Window with the official Schengen calculator
Use identical dates and modes, compare the first divergent day, and understand why the European Commission tool remains the primary arithmetic cross-check.
6 minute read
Who should use a Schengen 90/180-day calculator?
Distinguish ordinary visa-free and short-stay calculations from short visas with a lower limit, long-stay visas, residence permits, and other cases needing official advice.
7 minute read
EES vs ETIAS: what changes for the Schengen 90/180 rule?
Separate border registration from travel authorisation, understand their current 2026 status, and see why neither system creates a fresh Schengen day allowance.
United States SPT
7 minute read
The US substantial presence test day-count formula explained
Understand the separate 31-day and weighted 183-day gates, the exact three-year arithmetic, and why the result cannot settle a person's final US tax position.
7 minute read
What counts as a US presence day for the SPT formula?
Review the IRS any-part-of-day rule, the geographic scope of the United States, and the distinction between physical presence and separately reviewed excluded days.
8 minute read
US SPT excluded days and the Form 8843 boundary
See the excluded-day categories named by the IRS, why category eligibility cannot be automated from day totals, and where Form 8843 enters the separate review.
8 minute read
Closer connection exception and Form 8840: calculator limits
Understand the conditions the IRS asks a person to review, the timely Form 8840 process, and why a day-count estimator cannot decide a closer-connection claim.
8 minute read
Substantial presence test formula: five worked examples
Follow the IRS 120-day example, both formula gates, excluded-day subtraction, and exact unrounded sixths without turning arithmetic into a final tax conclusion.
United Kingdom SRT
7 minute read
UK Statutory Residence Test: the full-year decision order
Follow the statutory sequence from automatic overseas tests through automatic UK tests and sufficient ties, while keeping complex cases outside a day-count shortcut.
8 minute read
UK SRT day counting, exceptional circumstances and deeming
Separate ordinary midnight days, exceptional-circumstance adjustments, deemed qualifying days and the special no-deeming channel used by the overseas work test.
7 minute read
UK SRT automatic overseas tests and their review limits
Compare the prior-residence day thresholds with the full-time overseas work route without reducing work hours, breaks or special worker rules to a simple day total.
7 minute read
UK SRT automatic UK tests: days, homes and full-time work
Review the adjusted 183-day test first, then understand why the home and full-time UK work tests require factual periods rather than a presence-day shortcut.
8 minute read
UK SRT sufficient ties: prior-residence tables and limits
Use the correct prior-residence threshold bands and review each family, accommodation, work, 90-day and country tie without turning labels into automatic facts.
7 minute read
UK SRT split-year treatment: the mandatory review boundary
Understand why full-year residence comes first, how departure and arrival cases are prioritised, and why split-year and treaty effects remain outside an ordinary day estimator.
Canada tax residence
7 minute read
Canadian tax residence: factual, deemed and treaty layers
Follow the domestic residence hierarchy from ordinary life and significant ties to the limited deemed-residence rules, then keep any treaty analysis separate.
8 minute read
Canada's 183-day deemed-resident rule and sojourning limit
Separate physical presence, US commuter exclusions and qualifying sojourns before using paragraph 250(1)(a) as a limited calendar-year review gate.
7 minute read
Significant residential ties in Canada's factual residence review
Understand how a dwelling place, spouse or common-law partner, dependants and secondary ties inform an all-facts review without becoming a points test.
7 minute read
Canada tax-treaty residence: keep the tie-breaker separate
See how subsection 250(5) follows a domestic residence basis and why day totals cannot predict dual residence or an applicable treaty tie-breaker outcome.
7 minute read
CRA Forms NR73 and NR74: an optional residence-status opinion
Understand when the leaving and entering forms may be considered, why the resulting CRA opinion is non-binding, and what remains outside a calculator.