In Finland, all income is taxed. Your employer deducts the tax from your salary in accordance with the tax rate on your tax card. You can obtain a tax card from your tax office, and you must then take it to your employer. When you apply for a tax card, you must have a personal identity number or a temporary identity number, which which will be given to you bythe Administrative Council.
More information is available on the Tax page of the Info Bank.
Tax Offices are located all over Finland. You can find contact details of the tax office for your area from this website.
The website of the Tax Administration contains a vast amount of information on taxation in Finland in in Finnish, Swedish and English.