/ Tax in Poland?
There are some tricks - but our tax offices have better tricks, too. There are many stories about people destroyed by them. One of my father's collegues committed suicide (really sad story including the way he did it) after he decided to leave company and set up his own business. Tax office and ZUS killed him.. I know it is off topic - but...
Let's go to the point.
In Poland there are two government institution looking for Your money:
Urzad Skarbowy - responsible for collecting tax from employees and businesses.
ZUS - Zaklad Ubezpieczen Spolecznych - responsible for collecting money for social insurance purposes, like pensions, benefits, sick pays etc.
As long as You are employee Your employers takes care of all deductions due from Your wage, based on pay as You earn system. Employees responsibility is limited to sending once a year PIT form to local tax office, informing them about incomes, You can also apply for tax relief - there are few, every year less and less of them...
As I said before, Your wife's salary is quite good, so will be taxed proportionally, but we all pay taxes, so there is nothing to worry about.