Expected salary and cost of living

Please go through existing threads in https://www.expat.com/forum/256-9-tax-in-belgium.html

You will get an idea

Dear,

indeed taxes a very high in Belgium. As an engineer you're part of the better paid community here so expect to have something around 2500€ net (equals 4000€ brutto) + a company car + fuel card + meal vouchers 150€ per month + additional private health insurance.

Cost of living depends as always on your needs.
An apartment with one bedroom and a living room should cost you between 700€ (normal flat) and 1000€ (nicely renovated flat) without charges. The good thing in Brussels is that you usually always find nice flats close to nice parks and public transport. No need to live far outside like in other cities. Calculate additional 200€ for charges.
So you'd still have 1500€ on your bank account to spend it on food, clothes and vacations. (Or whatever you do with your money).
Calculate that going to a restaurant will cost you between 15 - 20€ per dish.

I hope I could help you!