First of all, you must report any changes in your income to the Bafög office. Then certain income limits apply. If you earn more than this, the additional income will be deducted from your Bafög. You can earn a gross income of 5,422 euros per year or 452 euros per month without it being deducted from your Bafög. Anything above this amount will be deducted from your Bafög. You can find detailed information on the topic of Bafög and additional income here. With a 450-euro minijob, students who receive Bafög are definitely on the safe side. Whether the job is related to your studies or not is irrelevant. The number of hours worked is also irrelevant for the Bafög.