If you wish to invite somebody to Belgium, and you wish to be financially responsible, you must sign a pledge of financial support.
You can obtain this document at the town hall where you are registered.
If you are registered with an Embassy abroad, you can obtain this document at the visa section.
Be aware : only the original document is valid.
This must always be submitted + 1 copy at the time of the request for visa.
For more information in French or Dutch concerning the pledge of financial support, you can click here.