Tax help. Not living in Belgium anymore, but... (Brussels)

Hi,

I used to live (in Flandres), work (in Brussels) and pay taxes in Belgium, I'm not a Belgium or EU citizen.
I moved to Germany about 1.5year, for a new job. So now I pay taxes in Germany.

For personal reasons, too complicated and long to explain here, I didn't unregistered myself from my city. I will do that around end of this year until some issues I still have to deal with are done. Buuuut, in the meantime, I got the yearly tax declaration on my mailbox.
Since I was still inscribed in the city, I guess I'm bound to fill in that tax declaration even if I don't work anymore in Belgium. So the questions are:

- I suppose I have to fill nothing in the "Vak III.A. Belgische inkomsten"
- However, at the last page there is a question "do you get paid in a foreign country?" Here is were I am not sure. Should I fill in what I earn (and already paid taxes) in Germany? or should I also just ignore this?

Anyway, after this is done, I will be officially unregistered in the coming months, so it is just for this time I need help. Any advice on how to proceed is very welcome.

Regards,
Karl