Why protect people from war or human right violations? If you look at it only from an economic standpoint, why pay for people whom we know will never contribute at all? Handicaps for instance. The UN refugee treaty guarantees safety for people whom are refugees conform the criteria. That's why they are welcome in the Netherlands. And if we let people in, they are part of our society, with all the benefits and drawbacks.
Let's keep these things ordered up and separate - protection and welfare.
Protection aspect is achieved by you letting them into your country and providing some legal status for them to live, work and contribute. Done. Welfare has nothing to do here. Now - it's a two-way street. Once a refugee is let into the country, they need to be explained how people live and work here, what are the customs and laws here like, and what is expected from them in return. First expectation - once they are out of the refugee "boot-camp", they must make it their priority (with help of authorities and volunteer organizations) to find work so that they upkeep themselves and pay a fair market rent for the place of their choosing. Second - they must work legally and pay taxes, just as everyone else in the country does. No work for cash common in migrant communities. If they open a business, the business must also be operated in a strict compliance matter. Lastly, and perhaps most importantly - they must not break the law, regardless - no fighting, violence, tax evasion, drug dealing, participating in organized crime, etc. Their rent must be paid on time, as well as public transit fare. And the state must be strong and clear about it - by accepting the refuge, you are entering the contract; you break it - you are out within 72 hours, regardless what's going on in your home country. If you are to accept refugees - only on these terms.
Speaking of providing welfare - you should not be putting that on all taxpayers. If you want, you can create a charity and collect donations for refugees support and welfare. But to do it or not - leave this decision up to the person that made the money, and don't take it away in form of taxes.