On days of national significance and commemoration for Latvia, admission to the Museum of the Occupation of Latvia is free of charge.
March 25: Commemoration Day of Victims of Communist Terror
May 4: Restoration of Independence of the Republic of Latvia
June 14: Commemoration Day of Victims of Communist Terror
July 4: Commemoration Day of Genocide against the Jews
November 18: Proclamation of the Republic of Latvia
While museum admission is free on these days, you can book a guided tour in Latvian, English or Russian for an additional fee.