Your tax residency,
defensible before any auditor.
The IRS, AEAT, or your home tax authority doesn’t ask for a calculation — they ask for proof. 183 días collects your evidence (flights, hotels, photos, workouts, passport stamps), signs it cryptographically, and anchors it to Bitcoin. Your history stops being a spreadsheet — it becomes a defensible record.
Encrypted on your iPhone · No servers · OpenTimestamps · DBLV LLC (Wyoming)
A spreadsheet won’t save you from an audit.
Every nomad does the same thing: a sheet with dates. When a tax authority reviews your residency, that sheet is worthless. Any expert witness can prove it was hand-editable in 30 seconds, and the case collapses.
What you actually need is the opposite: a chain of evidence that can’t be rewritten without leaving a trace. Boarding passes with signed barcodes, photos with EXIF GPS, Apple Health GPS tracks, receipts with tax IDs. You already have all of it — what you’re missing is grouping it, signing it, and anchoring it in time.
"In a residency-determination procedure, the burden of proof lies with the taxpayer."
Four layers of evidence, woven into a single chain.
Each piece of data enters through a different lane and anchors to the previous ones. Editing the past leaves an immediate trail.
Passive collection
Automatically imports from Gmail (Iberia, Booking, Airbnb, eDreams, Air Europa confirmations), Apple Health (GPS routes signed by iOS), Google Timeline (years of history), photos with EXIF, and Wallet boarding passes. You barely type — the app already knows your story.
Signed chain
Every border crossing is linked by SHA-256 hash to the previous one. Any edit to a past crossing invalidates every subsequent hash — it is mathematically impossible to rewrite your history without detection.
Bitcoin notarisation
Periodically, the current hash of your chain is anchored to Bitcoin via OpenTimestamps. An independent third party — verifiable by any expert — certifies that your chain was in that state on that exact date.
Annual probative report
A signed PDF with your full timeline, days per country, attached evidence, time-stamped by OpenTimestamps. Ready for your CPA, the IRS, AEAT, or a court of law.
The difference between a spreadsheet and a defence.
We don’t compete with day counters. We compete with nothing — and with expensive tax advisors who manually rebuild your history.
Premium because not having it costs much more.
A poorly defended residency audit can cost five figures in back taxes + penalties. This costs less than two coffees a month.
Free
Try it. Enough to get started.
- One country (Spain, USA, Mexico or DR)
- Manual day counting
- No Gmail import
- No signed chain
Plus
The sweet spot for serious nomads.
- Unlimited countries
- Gmail importers (6+ providers)
- Apple Health + Google Timeline + photos
- Interactive map + annual Wrapped
- AES-256 encryption + Face ID
Pro
Full audit defence.
- Everything in Plus
- Hash chain + Bitcoin notarisation
- Annual signed probative PDF
- AI assistant with your data
- What-if simulator + predictive alerts
- Form 8840 + Modelo 030 generated
- Family mode (spouse + kids)
B2B Advisor
For tax firms and lawyers.
- Up to N clients in read-only
- Aggregated dashboard
- Bulk PDF export
- Priority support
VAT excluded where applicable. Cancel anytime. No commitment.
Your data never leaves your iPhone.
AES-256 at-rest encryption
Your entire database is encrypted with a 256-bit key held in the iOS Keychain. Without your Face ID or passcode, the files on disk are noise.
No backend
We have no server that can be hacked, subpoenaed, or sold. Your history lives on your device. The only external connection is optional: OpenTimestamps to anchor your chain to Bitcoin.
Excluded from iCloud Backup
The app instructs iOS not to include your data in iCloud backups. Even if Apple received a court order, there would be nothing to hand over.
Panic mode
One tap at a border or customs wipes all device data and destroys the cryptographic key. The remnants on disk become permanently undecryptable.
Continuous audit
Every change to your history is logged in an append-only journal that cannot be edited — only appended to. Chain integrity is verifiable with a single tap.
European-operated US entity
Operated by DBLV LLC (Wyoming) with EU-based responsible party. GDPR, ePrivacy, all covered. We give you your data on request and delete it on request.
The real questions we get in our inbox.
Does this replace my tax advisor?
No. It makes them better: they receive a full file instead of half-remembered dates over WhatsApp. Your advisor still files the right form — but now with signed evidence instead of your memory.
Why is it defensible while a spreadsheet isn’t?
Because a spreadsheet is editable in 30 seconds without a trace. Our hash chain ensures any edit to a past crossing invalidates the entire chain — and Bitcoin anchoring (OpenTimestamps) gives certified-date proof of each chain state. An expert witness can verify it independently, with no need to trust us.
Does it work if I’ve been abroad for years with no digital history?
Yes. The app imports from Google Timeline (if you used it), Apple Health (years of GPS workouts if you wear an Apple Watch), Gmail (all past reservations), and EXIF photos. Most users recover 2–5 years of history in their first afternoon.
What if Apple disables HealthKit or Google kills Timeline?
Your data is already in the app, signed. Future imports would be blocked, but the history you already have remains valid. The chain stays intact.
What happens if I lose my iPhone?
Without the lost device’s Keychain key, the data is unreadable. If your iPhone is properly protected with a passcode and Face ID, no one will read it. To never lose history, we recommend periodically exporting the probative PDF and storing it externally (email, NAS, etc.).
Is it cheaper than a specialised advisor?
Much cheaper. A residency-specialised advisor charges €1,500–€5,000 just to rebuild your history. Pro costs €119/year. And your advisor will thank you: they prefer a ready file over chasing you on WhatsApp.
Is there an Android version?
Not yet. iOS first because of the ecosystem (HealthKit, Wallet, Vision for OCR, Photos). Android is on the roadmap with no date.
Which countries does it cover?
V1 covers Spain (183 rule + centre-of-interests presumption), USA (SPT with weighting and Form 8840), Mexico (183 + habitual residence), and Dominican Republic (favourable regime for foreigners). In 2026 we add Portugal, Andorra, UAE, and Switzerland by demand.
V1 is in closed TestFlight. When we open to the public, we’ll tell you.
No spam. One email when we hit the App Store and one when we launch each new language. That’s it.