Rules Update: No Tablebases In Correspondence Chess
Once again, you may no longer use endgame tablebases in daily chess.

Rules Update: No Tablebases In Correspondence Chess

Sep 7, 2018, 9:33 AM |

UPDATE (September 26th 2018):

In response to member feedback, as well as a long discussion within the team regarding these changes, we've decided to reverse our decision to allow endgame tablebases to be used in any forms of Daily Chess on our site. You'll note an updated rules section found here which makes clear that any forms of tablebase referencing will, once again, be considered a Fair Play violation. 

There will be a buffer period of 10 days for everyone to receive the message, after which tablebase use, if detected, may be met with an account ban. The only help you will be able to receive while in a correspondence endgame will be books and human analyses.

To reflect on what happened here, we can say that we tried this change based on the fact that it seemed as if our members were calling for it, but in hindsight, it seems we were unaware of how many would be opposed.

While the future of tablebases and deep, "tech-driven" analysis of chess is in some ways uncertain, what seems clear is that those tools like tablebases will only improve, solving more and more of our game (backwards to forwards). This experience has served, in many ways, as a wake-up call to help us at realize why we have Daily Chess and what makes it so special: the hard work and analysis from the past games and experiences of all humans, that we then use to help us play the best chess games we can...not engine evaluations or tablebase solutions on how best to approach a position.

We ultimately just want to ensure that our members have the best playing experience possible. We feel confident now that Daily Chess on is better without tablebases, and we apologize to all of our members both for the initial mistake of introducing the change, and for the confusion surrounding the issue.

Now, we leave you with a particularly concise comment that I very much enjoyed about our previous decision:


This one's for you, @ProphetessMio


Gerard Le-Marechal
Head of Fair Play on
Danny Rensch
Chief Chess Officer

(September 7th 2018)

Endgame tablebases have recently become an integral part of correspondence chess, to the extent that they are even used to adjudicate games in ≤6-piece positions in ICCF tournaments. It's been frequently expressed that such a tool should be allowed because it is a human-derived resource in the same vein as theoretical opening books. has decided to follow our members in embracing any-piece tablebases during all stages of your daily chess games. What this means is that during your own analyses, you will now be able follow a line all the way into a 6-piece position and check your tablebase to see if the position is winning, drawing or losing. is now working on setting up a new tablebase feature that can be accessed directly from analysis. For now, there are many online resources for you to look up a position, such as on k4it or chessok. I would recommend that you use those services instead of a tablebase connected to an engine which may lure you into accidentally accessing illegal engine analysis for a non-tablebase position.

Here may be as good a place as any to elaborate on some of the lesser-known rules of correspondence play:

  • You cannot receive help from another person in your daily games. Receiving advice from a tutor, friend or person over your shoulder is not allowed and may result in the closure of your account!
  • You cannot look at any pre-prepared engine evaluations you've compiled or written down. You may have put a lot of work into your opening theory with an engine, but to use those lines you will have to use just the moves themselves without the direct engine outputs.
  • You can access the analyses of human players in thematic games. If a popular game has been analyzed by a human player you may surely read their thoughts on the position as long as their analyses do not include engine evaluations.
  • With the legality of tablebases there is one best practice we'd like to introduce which is that despite the fact that tablebases are more accurate than engines, an engine should not be used to analyze positions with ≤7-piece positions. This is not exactly a rule, because we cannot enforce it, but we'd like you to separate engines from your correspondence play at all times.

For a full description of the rules of fairplay on you can head here:


Gerard Le-Marechal,
Head of Fair Play on