There should be absolutely no penalty for being married and having children. While there should be a reasonable increase in the matter of health costs, the need to try and encourage citizens to get married and have children to continue into the future is an important need for a country.
I do not believe it is right to tax married couples at a higher rate. I experienced this problem when I was married from 2002-2005. We didn't make much money but I instantly noticed the difference in taxes that first year. It was actually quite devastating, especially when they took my tax return money and handed it over for his child support arrears. The tax system in America has some very defined problems that make no sense.
To my knowledge, no one in the world is taxing married couples at a higher rate. The opposite is usually the case. Married couples are regularly given tax advantages over single people. There are some good reasons to encourage marriage. The best is that encourage people to make a legal partnership generally increases social stability. Also, married couples live together, reducing their expenses on housing, thus creating more disposable income. Disposable income generally stimulates the economy more effectively than money spent on housing (though to the detriment of local governments collecting property taxes on fewer locations).
I don't think it's fair to tax married couples at a higher tax rate, they have just as many expenses and bills then a single person does, I think taxes should be based on amount of the income that a person makes not because of the status if their married or not.
I do not believe it is right to tax married couples at a higher rate than any other couples. I think that the only thing that should determine if a married couple should be taxed highter than a couple who is not married, is if said married couple made more money.