The tax office will process the filed tax return and pay the overpayment within a maximum of 40 days from the day after the deadline for filing the tax return.
For tax returns filed by 31st of March, this is by 10th of May; for tax returns filed by the extended deadline, this is by 9th of June, 10th of July, 9th of August, 9th of September, 10th of October or 9th of November.