The following has been copied from our Policies section 7.4 - Dan Certificates and Grades :
The BGA monitors the progress of BGA members' ratings  and awards official dan certificates when specified targets have been reached. Official dan certificates are never revoked, even if a player's rating subsequently falls.
You will be awarded an X dan certificate when:
The easiest way is to email firstname.lastname@example.org  and ask.
Another way is to look at your individual results on the EGF site, via the BGA ratings list . The rating list shows your current strength and the EGF site shows how many games you've played and the ratings at the end of each tournament.
Note that since the strengths on the rating list are rounded to one decimal place, the threshold for promotion to, say, 3 dan, is actually 2.95 d.
Note that the conversion factor between rating and strength varies each month (as explained in the FAQ ). This means that it is possible for the strength of a player to change from 2.9 d to 3.0 d on the rating list  without playing in a tournament, but just because of small changes in the calibration and the effects of rounding. This is not good enough for a promotion. Certificates are only awarded due to changes in strength caused by tournament results.
The first time you play in a rated tournament, your rating is initialised to what amounts to a guess. Only after you have played in several tournaments does it settle down to reasonable measure of your playing ability. The final condition ensures that certificates are not awarded during this initial settling down period.
You can work out whether you have satisfied this final condition by looking at the table underneath your rating graph . This table lists all the rated tournaments you have played in, and for each one tells you (among other things) what your rating was after that tournament, and how many rated games you played during that tournament.
As a worked example, consider Tim Hunt’s rating graph . The relevant part of the table is reproduced here:
|Tournament Code||Class||Date||Description||Location||Club||Rank||GoR before -> after||Place||Rnds||Wins/ Losses/ Jigo|
|T020907C||A||2002-09-07||Northern Open||UK,Manchester||UK,MK||2d||2248 --> 2283||41 / 62||6||5||1||0|
|T020815||B||2002-08-15||Mind Sport Olympiad||UK,London||UK,MK||2d||2253 --> 2248||6 / 18||3||1||2||0|
|T020629E||A||2002-06-29||Welsh Open||UK,Barmouth||UK,MK||2d||2230 --> 2253||4 / 43||5||3||2||0|
You will see that Tim played in the Welsh Open, Mind Sport Olympiad and finally the Northern Open tournament on 7th September 2002. Together these constitute 11 tournament games (5 + 3 + 6). Before the Welsh Open Tim’s rating was 2230, and after the Northern Open tournament it was 2283, which is higher. Therefore Tim could be awarded a dan certificate any time from this Northern Open tournament onwards as the 3.0 dan strength at that time was about 2270. (Note: this dan promotion system only applied from 29th November 2003.)
So this condition will probably already be satisfied by any player who has worked their way up through the kyu grades while playing in European tournaments. It is most likely to affect strong players who play in a rated tournament for the first time when they are already of dan strength.
The EGF rating site  says:
If a rank professed by the player had improved significantly (at least by 2 grades for amateur players or by 1 professional grade) with respect to the highest previously professed rank, the rating of the player is reset. This measure helps to deal with fast improving players and with players who participate at included tournaments only occasionally.
Once a reset like this has happened, you must satisfy the “have a run of tournaments during which you play ten or more rated games, where your rating at the end of the run is at least as high as it was before the beginning of the run” condition again before you can earn a certificate.
This graph was generated from the 7th November 2003 European rating list. It shows the distribution of strengths of all European dan players at each dan grade (and 1 kyu). The white arrows show the thresholds at which BGA dan certificates are awarded. These thresholds are above the majority of players at the lower grade, and within, but near the bottom of, the main body of players at the higher grade. (Note: the Strength axis has been compressed above 7.3 d.)