Hi Farzan, In Estonia (and EU), the maximum period of stay of a foreigner on a long-stay visa shall not be longer than 548 days within 730 consecutive days. Therefore, if you apply for a DNV for the maximum period of 1 year, after that you can apply for a second DNV for a maximum period of six months. These would be two separate applications and decisions and, if you are successful in both, two separate stay visas. After staying in Estonia for 1,5 years you will be required to leave Estonia. Please note that staying in Estonia on a DNV has no advantage with regards to gaining any form of residence permit in Estonia.