Check with your local IRS office or a qualified U.S. tax accountant well before your departure, and ask them about all of the particulars relevant to Fulbright grants.

Please always check the most up-to-date information on the website of the Finnish Tax Administration. For further information, please see the English main page of the Finnish Tax Administration as well as information for the taxation of employees from other countries.
Lecturers and researchers should be careful to keep receipts for any expenses that may be tax-deductible, including those for postage, travel, hotels, restaurants, and equipment modifications. Graduate students are usually less able to recover these expenses.

Finnish Tax authorities provide advising services in English by phone. 
Tax service for specific International tax situations:
Calling from Finland, Tel. 029 497 024
Calling abroad, Tel. +358 29 497 024
You can also visit the local tax office in your host town in Finland. Contact city specific tax offices.
"Record your spending on professional matters during your Fulbright! You can deduct those expenses in your U.S. taxation." - U.S. teacher grantee 2017

If you need help with taxation issues while in Finland, the American Citizen's Services Unit at the American Embassy in Helsinki assists people with passport renewal, registration, Reports of Birth for children born in Finland to American citizens, voter registration, income tax forms, notary services, and emergency services. On occasion, the Embassy also has a tax consultant information session.
Your grant in Finland is paid for by Fulbright Finland, from an account in Finland. (The Specialist program grantees, the Distinguished Fulbright Awards in Teaching program grantees, and Fulbright-EDUFI Fellows program grantees are the exceptions to the rule). If needed, the "Grant Authorization" document which was sent to you for grant acceptance can be used for the American tax authorities. The Fulbright Finland Foundation does not inform the American authorities of the grants.

Please see more information about Fulbright Grant taxation in the U.S.
Please see more information for U.S. citizens residing outside the U.S. on filing their U.S. tax return.