The “Optimal” tariff is exclusively developed for participation in purchases with the published initial maximum price (IMC). In order to participate in purchases without IMC, Participants must activate "Partner" or "Winner" tariffs. However, in case the Participant already have effective "Partner" and/or "Winner" tariffs, he can apply for any purchases, including the ones with the published IMC.
The Optimal plan comes into force from December 23, 2024. You can learn more about the new plan at the link.