How to prove I have no income abroad?

[Holland]

Hello,

back in the day I registered myself at the social services (Kela), I was addressed a "foreigner taxation" because of my foreign background. However, since 2014 it's possible for Foreigners to get a progressive taxation too. The lady there told me at the time I needed to prove that I had no foreign income and then my Finnish salary would be taxed progressively, with tax returns. Does anyone know how I can prove this? Do I need to have my Dutch bank send a form, or does the tax application I have to send my Dutch government at the of this year suffice, even though I'll be in the Netherlands by then? I've tried googling it but I can't seem to figure out how to "prove" my Finnish salary is my only one.
any insight is appreciated!

Edit: I have found this article, but it doesn't state how I prove it, or that I even need to. Can I just get the form, have it filled in and be done with it?
https://www.vero.fi/en-US/Precise_infor ... esi(30756)

[FinnGuyHelsinki]

My guess is that you can prove it the same way you can prove it in the Netherlands that you have had income. Still, I would direct my questions to Vero first.

[Piet]

Hello,

back in the day I registered myself at the social services (Kela), I was addressed a "foreigner taxation" because of my foreign background. However, since 2014 it's possible for Foreigners to get a progressive taxation too. The lady there told me at the time I needed to prove that I had no foreign income and then my Finnish salary would be taxed progressively, with tax returns. Does anyone know how I can prove this? Do I need to have my Dutch bank send a form, or does the tax application I have to send my Dutch government at the of this year suffice, even though I'll be in the Netherlands by then? I've tried googling it but I can't seem to figure out how to "prove" my Finnish salary is my only one.
any insight is appreciated!

Edit: I have found this article, but it doesn't state how I prove it, or that I even need to. Can I just get the form, have it filled in and be done with it?
https://www.vero.fi/en-US/Precise_infor ... esi(30756)

No need to prove, you are either taxed in Netherlands or in Finland for any income earned there. Just choose in the Netherlands to be taxed in Finland. There is a Tax treaty that makes sure both countries (should) know about what you earn and to prevent double tax. Just state to the Finnish tax office that you have no income from the Netherlands and you want them to recalculate your tax percentage. If you don't, to much paid tax will be refunded at the end of the (next) year. At least that is how I did it with my Dutch employer in Finland. If you want to be sure you might want to copy your annual Tax form / decision from the Netherlands and give that to the Finnish tax office, no need for translation, that is their problem (just highlight the relevant amount of income and paid tax).

Correct me if I am wrong (then I can get more money back )