Expat double tax warning as expert lists 5 biggest mistakes | Personal Finance | Finance

An expat finance expert has revealed the five most common financial mistakes expats make when relocating abroad, and how to avoid costly consequences. Carl Turner, co-founder of Expat Tax Thailand, a tax advisory service for expatriates in Thailand, said Brits who want to move to another country often overlook the financial and legal complexities that come with it, and need comprehensive tax planning that goes beyond simple tax compliance to protect their wealth.

He said: “The same financial mistakes keep coming up. It’s common for people to assume their home country’s rules still apply, or that they can figure things out later. By the time they realise something’s wrong, they’re already facing fines or complicated paperwork.”

Tax residency rules vary by country and are often based on how many days you spend there each year, not citizenship.

“Expats are often unaware that spending 180 days or more in a country can trigger tax residency,” Mr Turner said.

“Once you’re a tax resident, you may owe taxes on your worldwide income in some jurisdictions.”

Without proper planning, expats can end up paying taxes on the same income in two countries.

“Double taxation is a real concern, especially for freelancers or remote workers,” said Mr Turner.

“You might pay tax where you’re living and again where your income originates.”

Brits are advised to check whether a tax treaty exists between their countries, look into foreign tax credits or exemptions, and work with a tax advisor to structure their income legally and efficiently.

Exemptions come with strict conditions, such as a maximum time period to claim the tax credit, a minimum time abroad or specific income types.

“People hear about exemptions and assume they’re covered,” the expert said.

“But in most cases, you still have to file and claim the tax credit.

“Without filing and claiming the tax credit, you could face a large unexpected tax bill.”

Expats are told to verify requirements, keep documentation and file correctly from the start, rather than fixing mistakes later.

In some countries, you need a local TIN to open bank accounts, sign rental agreements, or set up utilities.

But a lot of expats still delay this step.

“Depending on the country you move to, failing to register for a TIN can create real problems,” said Mr Turner.

“Without it, you may struggle to access basic services and could face penalties for not being properly registered.”

The specialist warned that different countries have different inheritance laws, and without proper planning, your assets could be tied up in legal disputes or heavily taxed.

“This is the mistake people realise too late,” Mr Turner said.

“Without a will or succession plan accounting for international laws, your family could face years of legal battles.”

He added: “These mistakes amount to more than just getting your tax return wrong. They can affect your ability to buy property, access healthcare, or even pass assets to your family.

“That’s why we encourage expats to think about tax and succession planning and not just tax compliance.

“It’s about understanding how all the pieces fit together: your residency status, your income sources, your long-term goals, and the legal systems you’re navigating.

“Getting professional advice early saves you time, money, and stress. The cost of getting it right is always less than the cost of fixing it later.”