Best App for Tracking State Residency in the US (2026): Features, Accuracy, and Legal Relevance

If you split your year across more than one US state, your tax residency is not a matter of where you feel at home. It is a matter of where you can prove you were, day by day. Take New York, one of the most aggressive states, which defines a statutory resident as follows:

Accurate as of 24 August 2026. Every statement about another product on this page comes from that company's own public materials (their website, App Store or Google Play listing) on that date. Where a company does not publish something, we say it is not stated in their materials rather than assuming it is absent. We do not publish App Store ratings in comparisons: rating counts differ so widely between products that side-by-side scores mislead more than they inform. Prices and features change, so check the linked sources before relying on any figure.

"You are a New York State resident for income tax purposes if: your domicile is New York State ...; or you maintain a permanent place of abode in New York State for substantially all of the taxable year and spend 184 days or more in New York State during the taxable year, whether or not you are domiciled in New York State for any portion of the taxable year."
— New York State Department of Taxation and Finance, "Income tax definitions" (accessed 4 June 2026)

That "184 days or more" line is the trap: cross it while a home is available to you and you can be taxed as a full-year resident. A contemporaneous, location-verified day log is the single most useful piece of evidence you can bring if that day count is ever questioned.

Several apps now compete to keep that log for you automatically. This guide compares the main ones for US state-residency tracking: TaxBird, TaxDay, Domicile365, Monaeo, Flamingo, and our own Days Monitor. The category is close enough that the right answer depends on your situation, so we have tried to be exhaustive and scrupulously fair.

How this comparison is sourced

Every factual claim about a competitor below is a direct quotation from that company's own public materials (its App Store listing or website), with a link to the source and the date we checked it (4 June 2026). We do not paraphrase competitor features or guess at them, because prices, ratings, and capabilities change. Where a tool does something we do not, we say so. The aim is the most complete and the most accurate comparison available, not a hit piece.

At a glance

This table reflects each app's own published feature lists, App Store pages and websites as of 4 June 2026. A dash or "Not listed" means the capability is not stated in those materials, not that it is necessarily impossible. Exact quotations and links are in the per-app sections and Sources below.

TaxBird

TaxBird focuses squarely on US and Canadian day-counting. In its own words, the app exists to:

"Stop worrying about counting days for tax residency. TaxBird automatically tracks where you spend your time throughout the year, helping you stay aware of residency thresholds before they become a tax problem."
— TaxBird, App Store listing (accessed 4 June 2026)

On coverage, the listing states TaxBird supports "Country-level tracking worldwide, State-level tracking in the United States, Province-level tracking in Canada, New York City residency tracking." Tracking runs in the background: "Using secure background location tracking, TaxBird keeps an accurate record of your days across multiple jurisdictions." At year end it can "generate a comprehensive report summarizing your residency days — ready to share with your accountant." Pricing is stated as "Annual — $39.99" and "Monthly — $4.99," after a "free 30-day trial." TaxBird's store listings describe country, US state, Canadian province and New York City tracking, and do not mention Schengen, the Substantial Presence Test or the UK Statutory Residence Test. Their website was not reachable to us on 24 August 2026, so this reflects what their store listings state rather than the full scope of the product.

TaxDay

TaxDay leans on the complexity of US state rules as its pitch:

"The US tax code is over 50,000 pages long. With TaxDay, you'll be able to easily monitor your travel with GPS against every US state residency tax code."
— TaxDay, App Store listing (accessed 4 June 2026)

It describes silent background tracking "using your phone's GPS, and a comprehensive database of state-by-state residency tax rules," now including New York City and, for international trips, "over 150 countries." Notable extras include "Receipt management: Attach receipts to your travel records," plus "Threshold notifications and alerts" and "Travel record export." Pricing after a "risk-free 45-day trial" is "$9.99 per month." TaxDay's own materials centre on US state rules and do not describe Schengen tracking.

Domicile365

Domicile365 spans both mobile and desktop, which its own site confirms. It describes itself as:

"Sophisticated Location Tracking for tax and other compliance purposes."
— Domicile365 website (accessed 4 June 2026)

It emphasises granular logging, stating location is "generally recorded in 15 minute increments using the highest level of accuracy supported by your phone," with "an unlimited number of day count alerts by Country, State, City, Possession or Province," and the ability to "email or download detailed day count logs (csv/excel and pdf formats)." It offers a "Sixty (60) day free trial -- no credit card required" and is "Available for Apple iOS, Apple macOS, Android, and our new Windows Tray App." That Windows and macOS support is genuinely distinctive: it is the only option here for someone who lives mostly at a desktop.

Monaeo

Monaeo is aimed at organisations rather than individuals. It positions itself as:

"Location Intelligence for Modern Workforce Compliance."
— Monaeo website (accessed 4 June 2026)

Its consumer-facing copy highlights "Track days in high-tax cities" and audit-grade reporting. If you are an individual taxpayer this is likely more tool (and more cost) than you need, but for an employer managing many mobile employees it is built for exactly that scale. We mention it for completeness; it competes in a different segment from the consumer apps above.

Flamingo Compliance

Flamingo combines residency, visa, and Schengen tracking in a single app:

"Flamingo Compliance flies with you and makes sure you comply with international, state, and city tax and visa requirements."
— Flamingo Compliance, App Store listing (accessed 4 June 2026)

For US state purposes it offers "Tax Residency & Domicile Tracking" with the ability to "Create separate trackers for achieving and avoiding tax residency in a country, state or US city," and city-level tracking that is "Currently only for NYC. More cities coming soon!" It also markets a Schengen feature, letting you "See how many combined days you've already spent in Schengen countries within the current 180-day period," and a visa index "synced in real-time with IATA database." It exports a "customizable CSV report." If your life spans US states and international borders, Flamingo and Days Monitor are the two that try to do both.

Days Monitor

Days Monitor is our own app, so treat this section as our pitch rather than a neutral review, held to the same sourcing rule. Our App Store listing describes it as:

"No more spreadsheets. Days Monitor automatically tracks every day in every country, for visas, tax residency, Schengen, US substantial presence, and any custom rule."
— Days Monitor, App Store listing (accessed 4 August 2026)

For US state residency it covers the same ground as the dedicated tools, with automatic background logging and US state statutory tests, and it adds Canadian provincial residency in the same app. A few things it does that the others, by their own listings, do not all do:

• Same-day multi-country logging. Our listing notes: "Cross a border in the morning and again in the afternoon? Days Monitor logs each country separately for the same date, with its own pin, time, and city."
• Rebuild history from photos. "Scan your photo library and Days Monitor recreates it from your GPS-tagged photos, processed entirely on your device." Useful if you need to reconstruct prior years for an audit.
• Custom rules for any jurisdiction, including "183-day tax residency rules," the "90/180 Schengen rule," and "US state statutory residency tests," alongside a "What If Trip Planner" for projecting future travel.
• Statute-based templates for 35 US states. The latest release ships ready-made day-count rules for 35 states, each sourced from the state's own statute, and describes them as "day-count templates for 35 US states, and fixed or rolling limits for anywhere on Earth" with the caveat that "templates are a starting point, not a ceiling": every threshold, window and alert stays editable. — Days Monitor for iPhone (accessed 4 August 2026)
• Reports for filings. "Export clean, timestamped travel reports, ready for accountants, lawyers, immigration advisors, or border authorities," in PDF and CSV.
• Privacy by design. "Your travel history is never sent to our servers," syncing instead through "your own iCloud, never our servers."

In fairness, several of these apps have been on the App Store for years longer than Days Monitor: TaxBird since 2017, TaxDay since 2016 and Monaeo since 2012. If a long track record is decisive for you, that is a real point in their favour.

How residency is defined varies by state, so the rule you track matters

We keep a full, sourced map of every state's threshold, including which states trigger at day 183 versus day 184, in The 183-Day Rule by State.

The threshold an app should track differs by state, because states define residency differently. Two big examples make the point.

New York applies two tests: domicile and statutory residency. It defines domicile as:

"the place you intend to have as your permanent home ... the place you intend to return to after being away."— New York State Department of Taxation and Finance, "Income tax definitions" (accessed 4 June 2026)

Even if New York is not your domicile, the 184-day statutory test quoted earlier can still make you a resident, so day-counting matters even for non-domiciliaries.

California does not lead with a day count at all; it uses a "temporary or transitory" standard. The Franchise Tax Board states:

"You're a resident if either apply: Present in California for other than a temporary or transitory purpose [or] Domiciled in California, but outside California for a temporary or transitory purpose."— California Franchise Tax Board, "Residents" (accessed 4 June 2026)

So a hard day threshold (New York) and a facts-and-circumstances test (California) call for different tracking. That is exactly why a tracker that lets you set the rule that applies to you, rather than assuming one threshold fits every state, is worth having.

Accuracy and legal relevance: what actually matters in an audit

For a day log to help in a residency audit, three things matter more than the feature list. First, the data should be captured contemporaneously and automatically from GPS, not entered from memory, which is why every serious tool here runs in the background. Second, you need an exportable, timestamped report you can hand to an advisor or auditor; TaxBird, TaxDay, Domicile365, Flamingo, and Days Monitor all provide exports in some form, per the quotations above. Third, the residency thresholds the app uses must match the rule that applies to you, which differs by state (the New York statutory residence test quoted above, "184 days or more," is the classic example). No app substitutes for professional tax advice, and none of the listings above claims to; they produce evidence, your advisor interprets it.

Which should you choose?

• US states only: TaxBird or TaxDay. Both are GPS-based and report-ready, per their listings quoted above.
• You live at a desktop or want Windows/macOS: Domicile365 is the only one here that lists Windows and macOS apps.
• An employer tracking many staff: Monaeo is built for workforce-scale compliance.
• US states plus international travel and Schengen: Flamingo or Days Monitor, the two that cover both.
• The most complete single tracker for a multi-border life: we built Days Monitor for exactly this, with same-day multi-country logging, custom rules for any country, photo-based history rebuild, and PDF/CSV reports, all kept on your own device and iCloud.

Whichever you pick, the important move is to start logging now: a residency position is far easier to defend with a full year of automatic, location-verified data behind it than with a reconstruction built under audit pressure.

Free calculators and full comparisons

Try our free tools, no account needed: the Schengen 90/180 calculator and the US Substantial Presence Test calculator. For head-to-head breakdowns, see TaxBird vs Days Monitor, TaxDay vs Days Monitor, Domicile365 vs Days Monitor, Flamingo vs Days Monitor and Monaeo vs Days Monitor.

Corrections

Every competitor claim here is checked against that company's own published materials and date-stamped. If you represent a product named on this page and believe anything is inaccurate or out of date, contact us and we will correct it promptly.

Sources

• TaxBird - Residency Tracker, App Store (accessed 4 June 2026)
• TaxDay, App Store (accessed 4 June 2026)
• Domicile365 website (accessed 4 June 2026)
• Monaeo website (accessed 4 June 2026)
• Flamingo Compliance, App Store (accessed 4 June 2026)
• Days Monitor, App Store (accessed 4 June 2026)
• New York State Department of Taxation and Finance, "Income tax definitions" (accessed 4 June 2026)
• California Franchise Tax Board, "Residents" (accessed 4 June 2026)