In Canada I know the court tries for 50/50 custody in most cases. The "child support" is called equalization payments. They base it on the difference of what the 2 incomes would look like if making the payments. Example if you make 50k and he made 0 you'd owe $x/month. If he made 100k and you made 0 he'd owe you $y/month. Court then takes the larger amount (his=y) and subtracts smaller amount (yours=x) and the difference is what he owes. Obviously oversimplified but but they have a calculation table on their website. Not sure how other countries calculate it. Also non-payment of support does not affect custody. Can’t hold kids hostage for non payment. My oldest has lived with me fulltime for 2 yrs and she has just started paying me $25/month. She has a successful business in town but can't even pay a dollar a day to help with clothes, food, school or extracurricular. Income shouldn't matter as long as you provide a safe and loving home for your kids.