Say I somehow make an illegal move, what happens? If I realize, can I then take it back, and make it legal? If so, how?

  • 3
    Can you precise what you mean by "make an illegal move legal" ? An illegal move is by definition, illegal. But if d2-d4 is illegal at some point because you have a bishop in the way on d3, then removing this bishop would possibly make a later d2-d4 legal. Maybe you mean smg else altogether, but you need to explain yourself.
    – Evargalo
    Aug 20, 2018 at 14:25
  • 2
    Yes, you need to explain. Another option to the one mentioned above: Under some rules, if you make an illegal move (e.g. leaving your own king under attack) and the opponent (or arbiter) points it out, you are forced to take back that move and make a legal move. Typically in such situations a time bonus is added to the opponent's clock. Aug 20, 2018 at 14:53
  • 3
    If you make an illegal move, and you notice right away, you are usually allowed to change it into a legal move. However, you need to move the piece that you touched if possible. (There is more to be said about this, but I am not sure this is at all what you want.)
    – quid
    Aug 20, 2018 at 15:35
  • 1
    -quid , yeah that's what i wanted
    – tah
    Aug 21, 2018 at 14:20
  • 1
    Honestly i meant every case imaginable .. but quid answered what i needed !
    – tah
    Jan 1, 2019 at 10:57

2 Answers 2


It is possible for a position to change in such a way that an illegal move becomes legal. As one example, if a move would result in your king being in check, then it is illegal, but if you make one (or more) move(s) so that later the same move would not result in check, then it becomes legal. The following diagram presents one such situation:

[FEN "q1k5/8/8/8/8/8/1Q6/1K6 w - - 0 1"]
[StartFlipped "0"]

1.Qa2 Kb7 2.Ka1

In the beginning position of the above construction, the white king cannot move to a1, since that would be check. However, if white first moved their queen onto a2, then they would be able to move their king to a1 later.


In blitz I believe if you make an illegal move and your opponent doesn't notice it, and then completes their move, the position stands as valid.

Not the answer you're looking for? Browse other questions tagged or ask your own question.