Short term work and residence registration

[CzRanito]

I'm an EU citizen, soon coming to work to Finland for about 4 or 5 months. After 3 months, I am required to register my stay at local police station (Both for staying in the country and for working longer than the registration-free period)

Will it be OK to register after 3 months as an employee who's going to stay couple more months, or do I have to report the intention to stay for work in advance ?
I read something about applying for some sort of work permit after these 3 months, when I am not allowed to work until it's processed, but now I don't know if it's related to this case... (Not really a permit needed, just some registration as well, I guess)

[rinso]

I'm an EU citizen, soon coming to work to Finland for about 4 or 5 months.

Registration (residence permit) gives you access to the horn of plenty in the Finnish social system. Most important the covering of medical costs.
Therefore it is beneficial to register as soon as possible. But if you don't plan on coming back and you have a medical insurance from your home country, you might consider not registering at all for such a short period.

[slinky1088]

However if you don't register you'll have to pay higher taxes I'm fairly sure. Because you don't have any kind of social security number. So it's better to register straight away, if you've got a job contract and you're an EU citizen then it's not a hard job at all. I think that's right. Somebody correct me if I'm wrong.