A player’s published (“official”) rating determines the section(s) in which she may or must play. A player’s published rating is static throughout a month and reflects her results at tournaments completed by the 3rd Wednesday of the previous month. Consequently, if a player wants to decide for which section she should register at any MCA tournament in March, for example, then she should look up her published rating in the USCF’s March Supplement. However, if the player wants to register in February for a tournament in March, then she just needs to remember that her unpublished rating on the 3rd Wednesday of February will be her published rating throughout all of March. Where a player’s published rating is static throughout a month, a player’s unpublished (“unofficial”) rating is variable within a month, in that it is subject to change each time a player competes at a tournament.
To look up a player’s published rating for the current month, go to: http://main.uschess.org/component/option,com_wrapper/Itemid,181/. (It will be listed below "Reg".)
Because a player’s unpublished rating reflects all of her most recent results, it is the more accurate reflection of her current skill level, if she competed at tournaments subsequent to those that determined her published rating. However, even though a player’s published rating can be a lagging indicator of her current skill level, the USCF and MCA use a player’s published rating to determine in which section she should play. Consequently, parents and coaches can register a player several weeks before a tournament, without having to worry about the possibility of her needing to switch sections at the tournament, as a result of her performance at an intervening tournament.
The United States Chess Federation’s Official Rules of Chess permits a Tournament Director to assign a rating to any rated player (Rule 28E) and revise the rating of any player at any time (Rule 28H). But only rarely will an MCA Tournament Director exercise these discretionary powers. Only if an MCA Tournament Director were to decide either that a player’s published rating, or that her status as an unrated player is extraordinarily unrepresentative of her current skill level, would the Tournament Director temporarily adjust the player’s rating or rating status—thereby requiring the player to compete in a different (presumably higher) section, so that she would be playing against players whose skill level is less incommensurate with hers.
A rated player is one whose rating has been published in a USCF Monthly Supplement; an unrated player is one whose rating has not been published in a USCF Monthly Supplement. Even though a player might have recently competed in USCF-rated games, she might still be unrated, because a published rating reflects a player’s results at tournaments completed by the 3rd Wednesday of the previous month. Furthermore, she might still be unrated, because she might not yet have fulfilled the primary requirement for obtaining a published rating: competing in at least 4 USCF-rated regular games (games that are G/30 or longer). Quick games like G/5 Blitz games affect a player’s quick rating, not her regular rating. A player has a provisional rating during her first 25 games. A provisional rating is indicated by a “P” after the player’s rating, listed beneath “Reg” (which is short for “Regular Rating”). A player has an established rating after the completion of her 26th rated game. Therefore, a player can have a published rating that is not yet an established rating.