Tax residency is no longer a day-count game. Authorities ask: can we credibly claim you based on your footprint, ties, and records. Build an audit-ready posture and documentation discipline, not a spreadsheet story.
When the question changes, the strategy must change
A founder we will call Leila thought she had solved the residency problem the modern way: a calendar, a flight log, and a home base where life felt lighter.
She ran her operating company from video calls. She kept a tidy spreadsheet of days. She took care not to cross thresholds that get repeated like folk wisdom at dinners: 183 days here, 90 days there. And she made one more move that felt like the final seal: she obtained a tax residency certificate in a low-tax jurisdiction. The paperwork looked official. The story looked coherent.
Then the friction arrived, not from a tax office letter, but from a bank.
A relationship manager asked for an updated self-certification of tax residence and an explanation for why most card spend, medical appointments, and recurring payments appeared in a different country than the certificate implied. Another compliance request followed: proof of address that was consistent across accounts, documentation for where decision-making actually happened, and a clean narrative for source of wealth. Leila did not feel accused. She felt audited by infrastructure.
This is the shift many high earners and globally mobile operators are bumping into. The question is no longer “How many days were you in Country A?” The question is “Can Country A credibly claim you, based on your footprint and the evidence trail you have already produced?”
Tax authorities have always cared about ties, intent, and the facts of life. What is changing is the intensity and visibility of claimability. Automatic information exchange, bank onboarding due diligence, and cross-checkable data trails mean your story is less private, less improvable after the fact, and more likely to be tested against reality.
In the UK, the Statutory Residence Test explicitly blends days with “ties” when the easy tests do not settle the matter. HMRC’s guidance shows how the number of UK ties can tip residence even at relatively modest day counts, depending on prior residence status.
In Spain, residence is not only about staying more than 183 days. Spain’s tax agency also looks to whether the “main core or base” of economic interests is located in Spain, and it can count “sporadic absences” unless you prove residence elsewhere.
Italy, too, frames residence around a mix of day count and civil-law concepts of domicile and habitual residence, and has issued updated administrative guidance in recent years that reiterates how facts and ties matter in practice.
And in the United States, federal tax residence runs on a distinct system, but state residency audits show the same underlying logic: if a state can demonstrate that your strongest connections remain, it can keep you claimable. California’s own published guidance describes residence as where your “closest connections” are, and notes the determination is fact-driven.
The common thread is not a single rule. It is an enforcement posture: claimability based on evidence.
The data trail is now part of the residency test, even when it is not written that way
Three forces have made claimability easier to assert:
1) Automated financial transparency became normal.The OECD’s Common Reporting Standard is designed for the automatic exchange of financial account information between jurisdictions, and it sets out what financial institutions report and exchange. For US persons, FATCA requires foreign financial institutions to report certain information about accounts held by US taxpayers or face withholding, while US taxpayers have parallel reporting duties.
2) Banks have become enforcement gatekeepers.CRS due diligence frameworks rely heavily on self-certifications of tax residence, with financial institutions expected to obtain and assess them. That means your residency narrative is not just a tax file. It is also a KYC file, and inconsistencies can become operational risk.
3) Audit evidence increasingly comes from lived-life records.State-level residency audit practices in places like New York illustrate the modern evidence reality: auditors may request credit card and bank statements, toll invoices, calendars, diaries, and travel itineraries to reconstruct location. In short: the evidence is already being generated by your daily life.
Many people lean on the idea that a tax treaty will settle everything. Treaties do help, but only when you qualify, only when both countries agree the treaty applies, and only after you have proven facts that map to tie-breaker criteria.
Under the OECD Model framework, the tie-breaker for individuals generally moves through a sequence: permanent home, centre of vital interests, habitual abode, nationality, then mutual agreement between competent authorities. That sequence is logical. It is also evidence hungry. “Centre of vital interests” is not something you declare, it is something you demonstrate.
Finally, not all situations are treaty-covered, and domestic law can still create serious friction even when treaty relief exists, especially when you cannot evidence the story cleanly.
Who this is for:High earners with cross-border life patterns, founders operating across jurisdictions, families with children in school, allocators with multi-bank setups.
Conditions that need to be true:
Think of your residency posture as an “evidence ladder,” not a day count:
HMRC explicitly tells individuals with UK connections to keep records that allow them to work out where they spent days and midnights, including travel schedules, booking information, and tickets.
Risks and frictions (do not skip):
The “deal” here is not a single investment. It is an operating system: advisors, compliance processes, and tools that reduce friction across tax, banking, and mobility.
Typical products and services that sit in this stack:
Ticket sizes vary widely. What matters is whether the output is defensible, consistent, and built for scrutiny.
Types of actors to speak to first:
Recommended sequence:
“Days are the easiest thing to count, and often the easiest thing to lose on.”
Key datapoints box:
Sources & disclosure:Key sources used: HMRC SRT guidance and record-keeping manual, Spain tax agency residency page, OECD Model Tax Convention update, OECD CRS publications, IRS FATCA overview, UAE FTA TRC service page. (GOV.UK)Standard
I-Invest disclosure: This article is for informational purposes only and does not constitute investment, legal, tax, or migration advice. Outcomes vary by jurisdiction and individual circumstances. Seek independent professional advice.
