Concerning multi-member constituencies, the Macedonian legislation provides for redrawing them in a way that each constituency will have 20 seats, based on the number of voters. The Parliament of Ireland revises the boundaries of the constituencies at least once in every twelve years. Changes they make do not take effect during the remaining time of the Parliament. In Malta, the Electoral Commission reviews the boundaries of the constituencies at intervals of not less than 2 nor more than 5 years. Parliament can then decide to alter the boundaries. In Bosnia and Herzegovina, the constituencies and the number of seats allocated to each constituency are reviewed every four years by the Parliamentary Assembly of Bosnia and Herzegovina to ensure that they are drawn, bearing in mind geographical constraints, in a manner that complies with democratic principles notably proportionality between the number of seats and the number of registered voters. In Bulgaria, the President of the Republic determines the constituencies no later than 56 days in advance of polling day. The Central Electoral Commission then determines the number of seats for each multi-member constituency based on a single standard representation for the entire country depending on the size of population provided by the National Statistical Institute, using the last census results, no later than 55 days in advance of polling day. No district will have less than 4 seats.