If you have an employment agreement with RWTH during your research stay and are here for more than six months, you are generally required to pay tax based on your global earnings.
If you will receive a scholarship, you should ask the funding organization whether you have to pay tax on this. You should also enquire as to whether the scholarship you will receive in Germany is subject to tax in your home country.
Income tax is directly substituted from your pay by your employer, i.e. the University, and paid directly to the German state; the amount of money withheld depends on your income, your family status, and your tax class.
Every individual who is registered in Germany is assigned a so-called tax ID number for life. You will usually receive this number in the mail one to two weeks after registering with the Residents' Registration Office and must notify the Human Resources Department of it immediately. At the end of the tax/calendar year, you can submit your tax return to the tax office. You may also submit this online. You can claim certain deductions in your tax return and may therefore receive a partial reimbursement of your taxes under certain circumstances.
A special feature in Germany is the church tax, which is collected by the state. Under certain circumstances, religious communities have the possibility to have church taxes collected by the tax office. For large churches, the church tax, which amounts to approximately 9 percent of income tax, is collected by the state together with income tax and automatically deducted from your monthly salary.
You must therefore state your religious affiliation when you register at the Residents' Registration Office. Members of the Roman Catholic Church, the Lutheran or Reformed Protestant Church, the Jewish Community, or certain Evangelical Free Churches must pay church tax in Germany. Members of the Anglican or Orthodox Church are not subject to the tax, however.