To file an annual report in Estonia, you can follow these steps: 1) Log in to the Estonian Business Register's online portal using your digital ID or Smart-ID, 2) Select the company for which you want to file the annual report, 3) Click on the "Annual report" button and then select the financial year for which you want to file the report, 4) Fill out the annual report form with the required information, including financial statements and management report. Once you have completed the form, submit the report and pay the required fee. Note that the deadline for filing annual reports in Estonia is six months after the end of the financial year.