One mistake could cost Brits thousands when they move abroad, an expert has said. A lack of proper tax planning, Carl Turner, Co-founder of Expat Tax Thailand, warned, means every year, countless expats watch thousands slip through their fingers. Not because of bad luck or poor financial decisions, but because of this simple oversight before they even board the plane. He said: “When it comes to protecting your money as an expat, it’s all about planning before you move, not after.

“Start by speaking to a tax adviser who understands both your home country and destination country rules, at least three to six months before your move date. They can map out the optimal timing for your relocation and any asset transfers. Keep detailed records of your time in each country, when you moved, and when you transferred assets. This documentation is vital if tax authorities ever question your residency status.

“Don’t assume tax treaties will automatically protect you.

“You often need to actively claim relief.

“And remember, every expat’s situation is different.

“What worked for your friend might not work for you. Get personalised advice based on your specific circumstances.”

Common consequences of poor planning

The expert listed the following five consequences of not properly planning your finances when emigrating.

• Double Taxation: You might end up paying tax on the same income in both countries. While tax treaties exist to prevent this, claiming relief requires paperwork, time, and often professional help, all costs that add up quickly.

• Losing Tax-Free Allowances: Expats often don’t realise they have capital gains allowances, dividend allowances, and personal savings allowances in their home country. Use them strategically before you move, and you can shield significant income from tax. Waste them, and you’re paying tax you didn’t need to.