Working in Finland as an International Student
An EU citizen can work while studying in Finland and does not need to acquire a special work permit to do so.
A non-EU -student who has been granted a residence permit for studies is allowed to work in paid employment in any field for an average of 30 hours per week. The number of working hours can be exceeded some weeks, as long as the average working hours are no more than 30 hours per week at the end of the year. Students are allowed to work full-time in any field also during holidays, provided that their average working hours are no more than 30 hours per week at the end of the year. A student is allowed to work for an average of 120 hours per month, or a total of 1,560 hours per year. (Migri.fi)
Earnings from part-time work during semesters may be included in the amount of disposable funds required for a residence permit at the discretion of the authorities. However, this is not possible in the case of a first residence permit.