legal cohabitation and cohabitation visa

Off you go to the commune ad start the process. They will be able to answer questions like that.

Be prepared for checks that this is a genuine long-term relationship and not simply a device for someone to get access to the EU.
You are likely to be asked to produce proof in the form of, for example, letters, emails, telephone calls, proof of visits back and forth to see each other and whatever else you can think of.

Just a word of warning, and I'm sure it's not relevant in your case, but you are aware of the consequences of legal cohabitation? I.e. legally, it is the same as being married, you become liable for each other's debts, it can impact your inheritance, you have to file a joint tax return, and a whole bunch of other stuff about the rights each partner has to occupy the family home, joint property and assets etc. etc. Basically it's the same as getting married, with all the rights and obligations that imposes on both of you. It shouldn't be considered lightly, just to help someone get a residence visa.

In an ideal situation you could of course get legal coahbitation while she is still in Belgium and then she would need to apply for visa in Belgian Embassy in her home country. But since Belgium is a wierd country and logic does not apply here, I would not suggest her to leave the country as the risk of visa being rejected is quite high. Just go to the commune and ask WHAT documents you need to sign legal coahbitation and apply for long-term residence. And if some person tries to give her/his judjment about who is legal or illegal here tell tham it not their business. They should concentrate on the work and help people in their situations.
Regarding legal cohabitation - I would disagree with ANON: yes it has a lot of implications and responsibilites, BUT it is way to far from being equal to marriage, and you can even cancel it unilaterally in case if there is need for that.
Good luck

It is a fairly complicated and lengthy process, at least it was when I did it a few years ago. It is easier if one of you is Belgian - I am not sure if you can get a visa if one partner is not Belgian (or possibly a holder of an EU passport from another country).
You can register your cohabitation at the commune, with all the paperwork that is required for your non-EU partner (proof neither of you is already married or in a legal partnership for one). While they work on the visa application (which will take 6 months) your partner can stay and work in the country on an orange card. You also have to submit your pay slips, employment contract, rental contract, etc to prove that you can support your partner in the country as you are financially responsible for them. There is also a requirement that they have medical insurance (which may be okay if they are already living in a European country).
For the application you will need to prove that you have known each other for at least 2 years and have a stable relationship (emails, texts, plane/train/bus tickets for trips together or visiting each other, etc - letters from friends are not accepted), or have lived together for one year previously, or have kids together. Your partner will also need some documentation from their home country (legalized birth certificate, criminal background check). The commune will submit all the documentation on your behalf to the ministry of immigration, and then you wait. At the end of 6 months, if you haven't heard anything (which is typical) it means that your partner can stay and you go to the commune to get your residence card.
Although it is complicated and will take time, it is doable! Your partner should also be able to stay for 90 days past the end of the residence visa depending on where they are from, as a tourist.

Hello Harry,
I was wondering if you started the process and your girlfriend is able to stay in the country while you are waiting for the decision, although she is on a expired visa?
My situation is the same, I will arrive on February but after 15 days, my visa will expire. Still, we will start Cohabitation process right after I arrive. So I'm wondering if I will be 'illegal'..
Your help would be much appreciated!

Hello all,

I applied for a cohabitation visa in the Belgian Embassy in the Philippines and I am now currently living in Belgium. I have declared legal cohabitation here in Antwerp with my boyfriend. I currently have my Orange Card and I am waiting for my F card. If you have any questions, I'd be happy to help.

Regards,
Kimy
www.gokimy.be