Day31 vs Daysium
A consumer privacy tool and an enterprise-grade evidence platform walk into the same residency audit. They are not really competitors — but you might be choosing between them.
The short version
Daysium positions itself as a tax-residency evidence platform for high-net-worth individuals and their advisors: automatic day counting plus geo-tagged, timestamped evidence, a shared advisor portal, and certified cloud infrastructure. It is aimed at people who expect to be investigated, particularly by HMRC. Day31 is for everyone who wants the counting without the apparatus: no account, no cloud, no portal — just an iPhone app that tracks every jurisdiction, works in airplane mode, and can rebuild years of past travel from your photos. If your tax affairs run through an advisory firm, ask them about Daysium; if they run through your pocket, Day31 is the fit.
Feature by feature
| Day31 | Daysium | |
|---|---|---|
| Tracking method | Automatic, on-device; no account or sign-up | Daysium Mobile app with automated day counting and geo-tagged logging |
| History rebuild | Rebuilds years of past travel from photo metadata in seconds | Positions itself around continuously built evidence going forward |
| Privacy model | No account; data never leaves the device; optional backup to your own iCloud | Cloud platform on Google Cloud infrastructure certified to ISO/IEC 27001:2022; Cyber Essentials certified |
| Advisor access | None by design — you share your own record if and when you choose | Daysium Portal: a live, shared view of your counts for your advisor (they see counts, not evidence or location) |
| Jurisdictions | Countries, US states, Canadian provinces, New York City, Yonkers, Schengen | Positions itself around UK tax residency and HMRC scrutiny; day counting across jurisdictions |
| Platforms | iPhone (iOS-native) | Mobile app plus web portal |
| Pricing model | Free download, optional Day31 Pro subscription (see App Store for current pricing) | Premium positioning; pricing not published on its site — talk to them |
Daysium details from daysium.com, checked August 2026.
Where Daysium is stronger
- The advisor portal. A live, shared view of your day counts for the professionals handling your affairs — no exported PDFs, no email attachments. Day31 has nothing like it, by design.
- Evidence framing. Timestamped, geo-tagged records built specifically to hold up when a tax authority asks questions — with expert partners in contentious tax publicly endorsing the approach.
- Certifications. ISO/IEC 27001:2022 infrastructure and Cyber Essentials — the compliance vocabulary that private-client firms and family offices are required to care about.
- UK focus. Built around HMRC's enforcement reality, with industry recognition (a Citywealth Magic Circle Awards 2026 runner-up) to match.
Where Day31 is different
- Nothing to breach. Day31's answer to data security is architectural: no account, no server, no copy of your movements anywhere but your iPhone and — if you enable it — your own iCloud.
- The past, recovered. Photo-metadata rebuild gives you years of travel history in seconds, before any forward-looking evidence log could exist.
- Self-serve and offline. Free to download, working in airplane mode, no sales conversation required.
- Breadth beyond the UK. US states, Canadian provinces, NYC and Yonkers, Schengen 90/180 — plus an interface in 33 languages.
Frequently asked questions
Is Day31 a Daysium alternative?
Only partly — they answer different questions. Daysium positions itself as an evidence platform for people whose residency will be contested: geo-tagged records, an advisor portal, and a compliance workflow. Day31 is a private day tracker: it counts your days across every jurisdiction, warns you before limits, and keeps everything on your iPhone. Many people need the second; some genuinely need the first.
Does Day31 have an advisor portal?
No — deliberately. An advisor portal means your data lives somewhere an advisor can reach, which means it lives on someone's server. Day31's architecture rules that out: no account, no cloud copy, nothing to share remotely. You can show or export your record yourself, on your terms.
Which is more private: on-device storage or ISO 27001 cloud?
They solve different threats. Daysium stores data on Google Cloud Platform infrastructure certified to ISO/IEC 27001:2022 and is Cyber Essentials certified — serious organizational security for data they hold. Day31 removes the question: there is no server copy to certify, breach, or subpoena, because your location history never leaves the device.
Does Day31 cover the UK Statutory Residence Test?
Day31 tracks your days in the UK (and every other country) and warns you as you approach the thresholds you set. The UK SRT's full tie-breaker logic is complex enough that we recommend our free web calculators and a qualified advisor for the determination itself — Day31 makes sure the day counts feeding that determination are right.
The record, without the infrastructure
Download Day31 free for iPhone — accurate day counts across every jurisdiction, kept entirely on your device.