A correctly prepared roster can still be operated wrongly, and in practice that is the commoner failure. The roster register is a live document: people join and leave, posts are created and abolished, and each of those events has a right answer that follows from the replacement principle. This part works through them.
The register and its two critical columns
The roster register carries, for each point: the recruitment year, the serial number, whether the point is reserved, the name of the person appointed, the date of appointment, whether that person is SC, ST, OBC or General, whether the post has been filled as unreserved or as reserved for a category, the signature of the appointing authority, and remarks.
Those two bold columns are different questions, and confusing them is the single most common roster error in Central Government establishments.
The first records the person's community. The second records how the post was filled. For most appointments they coincide. For a reserved-category candidate selected on merit they do not, and getting that case right is dealt with in Part 10.
When a post falls vacant
The replacement principle answers this in every case. The post carries the category earmarked against its roster point, and a vacancy at that point is filled by a candidate of that category, whatever caused the vacancy.
Retirement, resignation, death, and promotion out of the cadre are all treated the same way. An officer promoted to the next higher grade leaves this cadre; the post falls vacant; the post keeps its category. What happens to that officer in the higher grade is a matter for the higher grade's roster, which is a separate register with its own points and, for promotion, only two reserved categories in it.
The question to ask is never "how many reserved vacancies do we have this year". It is "which points are vacant, and what is each one earmarked as".
When the sanctioned strength changes
The roster is tied to the cadre strength, so a change in sanctioned strength requires the roster to be recast to the new number of posts, with entitlement recomputed for each category.
This is not the same as extending the roster. If a cadre grows from 40 posts to 60, you do not keep the existing 40-point roster and add points 41 to 60 to the end of it as though they were a separate tranche. You read the model roster from point 1 to point 60 and re-earmark the whole cadre, then map the persons currently in position onto it. Appending produces a different category distribution from recasting, and it is the recast one that is correct.
The same applies when posts are abolished. A roster that describes a cadre strength the establishment no longer has is simply out of date, and everything computed from it — entitlement, shortfall, the next reserved vacancy — will be wrong.
Determining the number of reserved posts
Cadre strength multiplied by the prescribed percentage, with fractions ignored. Not rounded — ignored. A cadre of 300 direct-recruitment posts gives 45 SC and 22 ST, because 300 × 7.5 per cent is 22.5 and the half is dropped.
This figure should agree with the count of points of that category within the first N points of the model roster. If it does not, check which roster you are reading and which mode of recruitment applies.
The single-vacancy rule
If only one vacancy arises in a cadre in a recruitment year and the roster point falling due is a reserved point, filling it from the reserved category would make that one post one hundred per cent reserved. The instructions deal with this expressly.
Where only one vacancy occurs in the recruitment year and the corresponding roster point is for a Scheduled Caste or Scheduled Tribe, it is treated as unreserved and filled accordingly, and the reservation is carried forward to the next three recruitment years. A year in which no vacancy arises is ignored when counting those three years.
This rule comes from Office Memorandum No. 1/9/74-Estt.(SCT) dated 29 April 1975, restated in Office Memorandum No. 36012/17/2002-Estt.(Res.) dated 6 November 2003.
De-reservation
In direct recruitment there is a general ban on de-reserving a vacancy reserved for SC, ST or OBC. The only opening is a rare and exceptional case in a Group A service where the post cannot be allowed to remain vacant in the public interest, and that route requires consultation with the relevant National Commission, a Secretary-level committee, and the approval of the Minister in charge of the Department of Personnel and Training. It is not a route that a Ministry can take on its own.
In promotion, de-reservation is permitted where a sufficient number of fit candidates of the reserved category is not available, and the power is delegated to administrative Ministries and Departments. The governing instruction is Office Memorandum No. 36020/2/2007-Estt.(Res.) dated 7 December 2009. Revised timelines issued in May 2026 extend the period a Ministry must wait for comments from DoPT and the concerned National Commission from two weeks to at least one month before proceeding.
A separate track exists for certain scientific and technical posts, which may be exempted from the reservation scheme altogether under long-standing instructions. That is an exemption from the scheme, not a de-reservation of a particular vacancy, and the two should not be confused in a noting.
A short worked sequence
A cadre of 20 posts, direct recruitment by open competition. Points 4, 8, 12, 16 and 19 are OBC; 7, 15 and 20 are SC; 14 is ST; 10 is EWS; the remaining ten are unreserved.
The officer at point 15, who is SC, retires. Point 15 falls vacant as an SC point and is filled by an SC candidate. In the same year the officer at point 3, who is General, resigns; point 3 is unreserved and is filled accordingly. The establishment then receives sanction for 10 additional posts. The roster is recast to 30 points, which adds OBC at 23 and 26, SC at 27, and ST at 28 — and the entitlement figures for the cadre change accordingly.
None of those three steps requires you to know how many vacancies arose that year. That is the whole point of the post-based roster.
Frequently Asked Questions (FAQ)
Q1. Which two register columns are most often confused?
The column recording the appointee's community and the column recording the category against which the post has been filled. They differ whenever a reserved-category candidate is appointed on merit without any relaxation: the first column records the community, the second records unreserved. Filling both with the community understates the shortfall and leads the establishment to under-recruit.
Q2. Do we extend the roster or recast it when posts are added?
Recast it. Read the model roster from point 1 to the new cadre strength and re-earmark the whole cadre. Appending new points to the end of the old roster produces a different distribution and is incorrect.
Q3. Is the three-year carry-forward the rule for all unfilled reserved vacancies?
No. The three-year carry-forward attaches to the single-vacancy rule only — where just one vacancy arises in a year and the roster point is reserved. Backlog reserved vacancies generally are treated under Article 16(4B) as a separate class and do not lapse with time; they lapse only when the category's representation in the cadre reaches the prescribed number.
Q4. Can a Ministry de-reserve a direct recruitment vacancy if no candidate is found?
Not as a general matter. There is a ban on de-reservation in direct recruitment. The narrow exception is a Group A post that cannot be allowed to remain vacant in the public interest, and it requires consultation with the relevant National Commission, a Secretary-level committee and the approval of the Minister in charge of DoPT. De-reservation in promotion is a separate matter and is permitted.
Related Reading
Next: small cadres and the L-shaped roster. The second exercise in the Reservation Roster Trainer is built around the situations in this part.