Divorce

There are no "fixed" percentages or allowances of any kind under Belgian law. It's all up to the two of you to decide what is reasonable, and to make and agreement to cover that. It will depend on how you split custody, whether the two parents work, etc. etc.
Basically the system in Belgium is now a "no fault" divorce system, where they take divorce out of the courts and place all the responsibility for negotiating the settlements / custody on the parents.
If you can't agree amongst yourselves, then you would have to go along the "désunion irrémédiable" course, where you get a judge to agree the terms of your divorce. This will take you a very long time and cost a fortune in legal fees.

You need to speak to a notaire. There is a pretty comprehensive summary in French here:
http://www.notaire.be/divorce-separation/le-divorce-en-general

I presume you are a man., If your children are indeed your first priority, you shouldn't be asking what percentage your should pay. to the other parent. Sometimes I wonder if the parent who walks away, understands how difficult it is for the parent who stays with the children. You are talking about a percentage and I am talking about giving up your whole life to be close to them every single second of the day. It is when they are finally grown up that a single parent collapses. In my opinion, every single parent, a day after the children fly the nest, should present the other parent with a huge bill for playing both roles for so many years. Find yourself a lawyer and he will tell you what percentage you should pay by law for your children. I dare you pay a euro more !!!

Oh Isabella, I could have not written that better. I don't think some parents who walk away in times of divorce know what it feels like for the children who they are effectively divorcing too, that suddenly it all becomes a question of money and not love. Then the remaining parent left often fighting for enough money to live on, whilst usually having to work, play the role of 2 parents, that parents gets accusations of being obsessed by money, made by those not in that position who haven't a clue what it's like for a partner to reject their partner and their children too. It's also perfectly acceptable for the parent left behind to have problems simply "accepting" they have to accept that's life, get on with it, accept what the leaving parent is prepared to offer - because no amount of money makes up for a parent leaving behind their children through their choice.

I agree 100% with Isabella and I!!!! If you are indeed thinking of the children in the first place why are you asking about money?

Maybe it's the parent being left behind? In which case money can be the difference between the children going hungry and eating. What some parents are willing to inflict on their children when they leave them is not actually believable by those who've never gone through it but yes, there really are parents who walk away and leave their children with nothing and empty the bank accounts and go on spending sprees, spending all that was saved up for their children. Then you think, who is the child?

If you are the parent thinking of leaving, you shouldn't be asking how much the children should be paid, you should be asking how little you can live on so that your children have the same standard of living as before you left AND you should be thinking of why you are prepared to leave your children.

Very judgemental replies not knowing the circumstances -- see a notaire and the main thing is that there is a fair (to all sides) resolution. (I can't see anything in the sparse details the OP provides that he/she is planning to walk away -- which seems to be the presumption of all the responders except the first one)

"should that parent get the kids" means one will not, it's 50/50 here unless good reason not to be or unless one parent doesn't want to parent.

Hard times Roth and of course financial matters are a concern. So many other things to think about and I'm sure your doing this and just asking this particular question rather than only being concerned about this.

If you want to stay here and want the kids to do so (mandatory 50/50 time split unless otherwise agreed, proven alcohol/violence abuse, kids over 13 (ish) wanting different) get a lawyer fast and get the divorce appeal lodged here ASAP before an appeal is lodged elsewhere.

Money will be fairly partitioned by the courts, don't agree to anything under partner pressure (for the good of the kids etc). Stand your ground for what you want, if it's fair then there is a good chance it will happen, eventually.

I hope that helps and you are right to worry about the money, it often is bitter, bitter battlefield during divorce.

I think it is unfair if anyone here is being judgemental - I for one don't know your circumstances. You wanted advice on a particular matter, 'tis all.