Castling Move Restrictions
Basic Castling Restrictions
The basic setup of the pieces on the first rank is required:
- Cannot jump over any pieces between the King and Rook. All the squares must be empty between your King and Rook.
- Cannot capture any pieces while castling. If there are any enemy pieces between your King and Rook, you cannot castle.
- The King and Rook must both be on their original squares.
Check-Related Castling Restrictions
Here’s a list of rules about “checks” that prevent or disallow a castling:
- Cannot castle out of check. You are not allowed to castle if your King is in check.
- Cannot castle into check. Obviously, if the move results in check to your King, it’s an illegal move.
- Cannot castle through check. This is a tricky one. If the empty square through which the King would travel are attacked by an enemy piece or pawn, you cannot castle. So the King cannot jump over a checked square, even if it’s not currently in check, and the king’s destination square is not in check.
King or Rook Have Previously Moved
Previous moves in the game also restrict castling:
- King has previously moved. If the King has moved at any time previously in the game, castling is disallowed forever. It’s still disallowed even if the King moves back to the original square later.
- King not on its original square (obviously, it’s moved, so castling disallowed by the previous rule.)
- Rook has previously moved. That rook cannot castle it is has moved in the game, even if it has moved back to its original square. (But the other rook can still castle if it hasn’t moved.)
Basic Castling Restrictions
Some of the castling restrictions are pretty simple:
- You cannot 3-square castle or 1-square castle. Only 2-square castling is allowed. The King moves exactly 2 squares towards the Rook, and the Rook jumps over to sit right next to the King. This 2-square rule applies to castling on either side.
- You cannot castle twice.
- You cannot “un-castle”. There’s no such “reverse castling” move.
Not all things prevent castling. For example, you can still castle, even if:
- King was checked earlier (e.g. two moves ago or twenty moves ago), provided that the King is not currently in check and that the King did not move earlier (i.e. it was checked, but you blocked the check, or captured the checking enemy piece.)
- Rooks can castle through a checked square, so long as the King doesn’t travel through that square. This only occurs on Queenside castling when the "b1’ or "b8’ square is attacked.
- The other Rook previously moved. If one rook has moved, you can still castle on the side of the rook that hasn’t previously moved. But moving the King disallows both sides.
Related Chess Rules Topics
Read more about these related chess rules, chess puzzles, and other chess tactics and strategies: