Register in the commune or not?

....... "no real obligation to register in your local commune? Is this the case?"

No it is not the case at all.

If you intend to reside in Belgium you have to register. It is the law.

If you don't register, you won't get a national number, and therefore you won't be able to work, as you're not in the tax system.
The ID card or passport from "another country" has nothing to do with Belgium.

Even Belgian citizens have to register.

You have no choice, Belgian law requires that if you start living at an address in Belgium, with the intention of staying in Belgium for three months or more, you have to commence the registration process at your local commune within 8 days. Failure to register is an offence and can result in very considerable fines, not least because you will be seen as a tax evader.
The requirement doesn't contravene the EU freedom of movement rules because it applies equally to Belgian citizens, although EU citizens can, if they wish (and are stupid), decline to have a Belgian "E" eID card. Note that if you don't have an eID card you must carry your passport (or the ID card of another state) at all times.

You need to register if you plan to reside or work here. Otherwise you remain a visiting tourist.

Hi All,

I have left Belgium and i am looking to deregister my resident card. Is there any email id where i can send an email to deregister. Or any specific person of commune to send the card with courier.

Thanks

Deregistering resident card of Belgium, Brussels (Louise Commune)

I think you must have heard about the EU people which are registered via the foreign ministry and they do not have to register via the commune. However, they get a special ID so they are legal. This is not valid for non-EU people.