The South Dakota Trick: How US Expats Can Avoid Unnecessary State Taxes

Most Americans moving abroad spend months researching foreign visa requirements, housing costs, and banking options. Very few think about their state driver's license - and that oversight can cost them years of unwanted tax notices, correspondence, and in some cases, a tax bill from a state they haven't lived in for years.

Taxes are painful enough. Paying taxes to a state you don't even live in is something else entirely.

Why State Tax Residency Is Different from Federal

Before we get to the strategy, it's important to understand why this issue exists in the first place.

As a US citizen, you're subject to federal income tax no matter where in the world you live. Citizenship-based taxation means moving abroad doesn't change your federal filing obligations - though tools like the Foreign Earned Income Exclusion (FEIE) on Form 2555 can significantly reduce what you owe.

States, however, operate differently. Most states tax based on residency, not citizenship. That sounds like good news - but the definition of residency is where things get complicated.

Most states rely on a legal concept called domicile: your permanent home, the place you intend to return to. The critical word is "intent." Even if you physically leave the country, a state can argue that your move is temporary or transitory - and continue treating you as a resident taxpayer until you prove otherwise.

Some states are much more aggressive about this than others. California, in particular, is known for being extremely sticky when it comes to releasing residents, but it's not alone. And the burden of proof often falls on you.

What "Breaking Domicile" Actually Requires

To establish that you've left a state's tax jurisdiction, you need to sever as many ties as possible. That typically means canceling subscriptions and memberships tied to the state, surrendering your voter registration, and ideally, no longer maintaining a home that's available to you for use.

The problem is that one of the most common pieces of evidence a state looks for - and one of the hardest for expats to surrender - is the driver's license.

Consider a real client scenario: a US expat who moved to the Middle East, married a local, had children who attended school there, and built an entirely new life outside the US. By any reasonable measure, Alabama was no longer their home. But when Alabama's tax authority came calling, their entire inquiry centered on one question: show us a driver's license from another state.

There's nothing in the tax code requiring a driver's license to prove domicile. But states know it's a practical shortcut - and they can drag out correspondence long enough that fighting it becomes more expensive than simply paying the disputed tax. That's the leverage they use.

The solution, in that case and many others, was a South Dakota driver's license.

How the South Dakota Trick Works

South Dakota is one of a small number of states that has built a system specifically for people without a fixed permanent address - originally designed for full-time RV travelers and those who move frequently without settling in one place. Expats can use the same system to their advantage.

Here's why South Dakota works well for this purpose: it has no state income tax, and it offers a uniquely accessible path to establishing driver's license residency without requiring a traditional physical residence.

The process works as follows.

First, you establish a mailing address in South Dakota. This can be a virtual address - there are services that provide exactly this for travelers and expats. You don't need to own property or sign a lease.

Second, you spend one night in the state. A hotel receipt or Airbnb confirmation showing your stay at a South Dakota address is sufficient. You don't need to establish anything beyond that single overnight visit.

Third, you visit a South Dakota DMV location with your standard identification documents - Social Security card, birth certificate, and whatever else the state requires, which you can confirm on their website. In place of the typical proof-of-residence documentation that would otherwise be required, South Dakota offers an affidavit of residency. This affidavit functions as an official acknowledgment that you're using a virtual or mailing address as your residency address for driver's license purposes. South Dakota explicitly allows this.

The result: a valid South Dakota driver's license tied to your mailing address. For the expat in Alabama, presenting that license ended the state's inquiry entirely.

One important update to note: South Dakota recently changed its voter registration requirement to 30 days of physical presence if you want to vote in the state. That doesn't affect the driver's license process, but it's worth knowing as you think through the full picture of what establishing ties to South Dakota involves.

When This Strategy Makes Sense

This approach isn't necessary for every expat. If you're moving to a country where you'll obtain local residency status and a foreign driver's license - say, you're settling in Mexico on a permanent resident visa, or establishing residency in Portugal - you'll likely have a clear paper trail showing your new domicile. A Mexican or Portuguese driver's license, combined with other residency evidence, will go a long way toward demonstrating that you've left your prior state behind.

Where the South Dakota strategy becomes particularly valuable is for expats who are in transition - bouncing between countries, not yet ready to establish permanent residency elsewhere, or living in a place where obtaining a local driver's license is a slow or complicated process. In those situations, you may be exiting a state like California with no clear documentation of where you've landed, which is exactly the scenario that leaves people exposed.

The South Dakota driver's license doesn't need to be a permanent solution. It simply provides a defensible, documented anchor point that demonstrates your intent to leave your prior state - without requiring you to have fully established yourself somewhere else.

This Is Proactive Planning, Not Cleanup

One of the most important things to understand about state tax residency issues is that they often surface years after the fact. A client moves abroad, files their returns, and then two or three years later receives a notice from their former state demanding proof that they weren't a resident in a prior year. By that point, the documentation burden is real, and the options narrow quickly.

Getting your state tax residency documented properly before you leave - not after a notice arrives - is the difference between a five-minute response and a months-long correspondence battle. It's the kind of planning that's easy to overlook in the excitement of an international move, but it matters.

This is precisely the work that goes into our Tax Confidence Package at McGowin Tax. It's not just about filing accurate returns. It's about building the documentation foundation that protects you against future inquiries from the IRS or state tax authorities - so that if a notice ever does arrive, your response is ready.