C.A.S.

As per G.O. No. 3015-F dated 13.03.2001, Rule 2 (iii),

A Govt. employee who has got promotion to a post in the first higher scale within eight years of service will have to complete total service of sixteen years before he gets advancement to the second higher scale with reference to the feeder post, provided he does not get any further functional / non-functional promotion in the mean time. He will get advancement to the third higher scale with reference to the feeder post on completion of total service of 25 years without any further promotion /appointment to higher scale of pay.

Thanks but if I get a further functional promotion before completion of 16 years service, should I have to wait for 25 years for further non functional promotion?

No. The above 8/16/25 years CAS is not applicable for High School Teachers.
As per Memo No. 181-SE /5B-1/09 dated 08.10.2009, All teaching nd non-teaching employees of Non-Govt. Sponsored / Aided Institutions shall be entitled to an additional increment in the revised pay structure @ 3% of pay in the pay band and grade pay taken together for every 10 years of continuous and satisfactory service counted from the date of first appointment to the same post subject to a maximum of two such increments during the whole career in addition to the benefits which may be admissible to him/her – both functional (due to appointment as Headmaster / Headmistress / Asstt. Headmaster / Asstt. Headmistress / Head Teacher) or non-functional (due to benefits of 18 years of service).
Note: As to the post of Headmaster is not the first appointment, nor it is a promotional one, it should not be considered separately for awarding any benefit of 10/20 years as was being done earlier. But the old cases settled earlier need not be reopened and the teacher may be allowed to submit option regarding his/her pay (which he is actually drawing) granted earlier. Similarly, the fixation of pay of Headmaster should also be not done with one additional increment as it is not a promotional post.

I am a panchayat employee. My joining date 09.10.2002. And I got a promotion 01.12.2011. Now when should I get the next non-functional promotion? I am waiting for your reply.

We, the panchayat employee of west bengal are not counted as government employee. We get 10/20 of cas not 8/16/25. But if you have the related order of 8/16/25 for panchayat employee then I would like to request you to share the same for us.
Thanks.