Research has shown that accents become permanent around the age of 12 years old. That being said, it is possible for accents to change over time or for adults to develop a subtle accent after living in a foreign country for an extended period of time.

Can you develop a different accent?

Your natural accent results from a system of sound patterns in your native language that you unconsciously learn as you grow up. ... Your accent can change early in life as you're exposed to different accents and speech patterns. But after your teenage years, your phonetic system stays mostly fixed.

Can you develop an accent later in life?

Research shows that if you start learning a language later in life (after the age of seven or later as an adult), you might become fluent but you won't be able to change your accent. You'll have more chance of changing your native accent in your native language, but even that will be difficult.