I built Southbound because I couldn't find an app I'd trust to track my parents' Florida days.
My parents started spending most of the year in Florida a couple of years ago and claim Florida residency on their taxes. They had no documentation of it that would hold up in a state audit.
I went looking for an app to fix that. The whole reason you build a contemporaneous residency record is to defend yourself in an audit. I wanted to build the record without keeping a developer-held copy of my parents' location history.
So I built Southbound. It runs on the phone. The data stays on the phone and in your own iCloud account, and you choose where exports go. My parents were the first users. Other people who travel for the same reasons are the next.
Who's behind this
Southbound is built and maintained by Ryan McKinnon, an independent software developer. I'm not a CPA, I'm not a tax attorney, and nothing on this site is legal or tax advice.
I read primary statutes and audit guidance directly instead of summarizing other tax blogs. What I'm actually good at is the evidentiary side — what auditors ask for, what formats they accept, where most people leave gaps.
When a question needs a credentialed answer, I'll cite a CPA or tax attorney and link them. When it doesn't, I'll show my work.
What this site is and isn't
Southbound Journal covers state tax residency, with a focus on Florida and the states people leave. It's background reading to help you go into a conversation with a CPA or tax attorney better prepared. It's not tax advice and it's not a substitute for one.
We don't take affiliate revenue from any of the CPAs, attorneys, or services we link to. We don't accept sponsored posts. We don't run ads. The only thing this site sells is the Southbound app.
How we research
Every article is built from primary sources: state revenue department publications, statutes, published Tax Court opinions, and audit guidance documents.
When a state law changes, the affected posts get a Last reviewed date bump and a changelog note. The most-trafficked posts also get a routine review every six months.
If you spot something out of date or wrong, write us — see Contact below.
Privacy is the product
Southbound records Florida days in the background on your iPhone. Your day count, timestamps, and location samples live on your phone and sync through your personal iCloud account when sync is on.
Southbound does not operate a server that receives or stores your location history. The app uses Apple's network-based geocoder to determine the state from coordinates. Apple and RevenueCat process purchases and subscription status.
We chose this design because the record is sensitive.
Full details: Privacy Policy.