Census puts population of Tallinn at under 400,000

I'm gatreful you made the post. It's cleared the air for me.

That is definitely true, even I've got experience with such, as well as a friend of mine.

In my case, I was an exchange student in Estonia back in 2009 and was registered in Tartu. Fortunately, when I left, I made it known to the population register that I had left so therefore my movement outside of Estonia was documented. A friend of mine (fellow exchange student) was here for 1 semester and didn't remember to un-register himself with the local registrar. He went home after 6 months and when he returned for his master's degree, and had to re-obtain his residency permit, he was documented as a resident in Estonia between 2009-2011 when he returned, although he wasn't here at all.

Now that is just in the case of exchange students. And I'm sure most do not un-register themselves locally after they leave.

In addition to exchange students, you have foreign workers, people who move out of the city, those who move into the city, people who come for work for a period of time, etc. etc. etc.

Those people will be added to the register, but most likely not removed. After 10 years, well... it is only logically obvious there would be a surplus as far as population is documented compared to real population.