District Collector vs DM vs SDM

A District Magistrate (DM) heads the magistracy of a whole district, and a Sub-divisional Magistrate (SDM) is in charge of one sub-division of it, under the DM. Both posts come from section 14 of the Bharatiya Nagarik Suraksha Sanhita, 2023 (BNSS), the central law on criminal procedure: the state government appoints one of a district's Executive Magistrates as District Magistrate and may place one in charge of a sub-division as SDM. All Executive Magistrates in the district, the SDM included, are subordinate to the DM (section 17).

The Collector is a different post, created not by the BNSS but by each state's land revenue law. None of the three is a rank of the IAS; they are posts. In many states one officer holds both district posts, and what the office is called depends on the state.

The District Magistrate: a post under the BNSS

Section 14 of the BNSS lets the state government appoint as many Executive Magistrates in each district as it thinks fit, "and shall appoint one of them to be the District Magistrate". It may also make any Executive Magistrate an Additional District Magistrate, with such of the District Magistrate's powers as it directs. If the post falls vacant, the officer who temporarily takes over the district's executive administration exercises the District Magistrate's powers until the state orders otherwise.

Subject to the state government's control, the District Magistrate defines the areas of the district's Executive Magistrates and shares out their work (sections 16 and 17). The powers that come with the post, from public order to inquests, are set out in IAS powers and functions. Nothing in section 14 requires the District Magistrate to be an IAS officer.

The Collector: a post under state revenue law

Land revenue is run under each state's own law, so the Collector's post is defined state by state.

• Maharashtra. The Maharashtra Land Revenue Code, 1966 says the state shall appoint a Collector for each district "who shall be in charge of the revenue administration thereof", with a Tahsildar for each taluka (section 7). All revenue officers in the district are subordinate to the Collector (section 11). If the Collector cannot act, the Additional Collector, or failing one the highest-ranking Assistant or Deputy Collector, takes over the office for the time being (section 10).
• Punjab. The Punjab Land Revenue Act, 1887 lists the Collector among its classes of revenue officers and says the Deputy Commissioner of a district is its Collector (section 6). So in Punjab, the officer known as the Deputy Commissioner holds the Collector's office under the Act.

One office, many names

The IAS (Pay) Rules list the district post in each cadre among the posts carrying pay in the Senior Scale. The titles they use show how much the name varies:

Title in the pay rules' Schedule II	Cadres where the schedule uses it (examples)
Collectors and District Magistrates	Andhra Pradesh, Telangana
Collector and District Magistrate (in various orders)	Bihar, Goa, Rajasthan, Tripura, West Bengal; Odisha and Sikkim in the plural
Collector, Collectors or District Collectors	Chhattisgarh, Gujarat, Kerala, Madhya Pradesh, Maharashtra, Tamil Nadu
District Magistrate(s)	Uttar Pradesh, Uttarakhand
Deputy Commissioner(s)	Assam, Haryana, Himachal Pradesh, Jammu and Kashmir, Karnataka, Manipur, Meghalaya, Nagaland, Punjab
Deputy Commissioner (Districts)	Arunachal Pradesh, Mizoram, Andaman and Nicobar Islands, Chandigarh, Delhi

These titles are from DoPT's published copy of the rules, and the Government amends the schedules from time to time. Where the schedule's title combines "Collector" and "District Magistrate", the cadre post carries both. Elsewhere, the state's own orders say who holds which.

The SDM, and the SDO

The sub-division has the same split between two laws:

• Sub-divisional Magistrate. Under section 14 of the BNSS, the state government may place an Executive Magistrate in charge of a sub-division, "and the Magistrate so placed in charge of a sub-division shall be called the Sub-divisional Magistrate". The state may delegate this power to the District Magistrate. Other Executive Magistrates in the sub-division are subordinate to the SDM.
• Sub-Divisional Officer. Under Maharashtra's revenue code, the Collector may place an Assistant or Deputy Collector in charge of one or more sub-divisions, and that officer "may also be called a Sub-Divisional Officer" (sections 2 and 7).

Neither law requires an IAS officer. In some cadres the pay rules do list sub-district posts for the IAS, such as Sub-Collectors Grade-I in Kerala and Sub-Collectors in Tamil Nadu. LBSNAA's district training includes attachments to SDM offices and, in some cases, independent charge as SDM, and its Phase II page describes being an SDO as the trainee's first posting. The posting itself is the state government's decision.

Executive and Judicial Magistrates

The DM and the SDM are Executive Magistrates, which the BNSS lists as a class of criminal court separate from Courts of Session and from Judicial Magistrates of the first and second class (section 6). The state government appoints Executive Magistrates (section 14); the High Court appoints the presiding officers of Judicial Magistrates' courts (section 9).

The BNSS also divides their work. Where another law gives a Magistrate functions that involve weighing evidence or can lead to punishment or detention, a Judicial Magistrate exercises them; administrative or executive functions, such as granting a licence or sanctioning a prosecution, go to an Executive Magistrate (section 3). Unless the context requires otherwise, a reference in any law to a "Magistrate of the first class" means a Judicial Magistrate of the first class. The sub-division has a judicial post of its own: the High Court may designate a Judicial Magistrate of the first class there as the Sub-divisional Judicial Magistrate (section 10), which is not the SDM.

Above the district

Revenue codes also create a level above the Collector. In Maharashtra, the state appoints a Commissioner for each division, who is the chief controlling authority in revenue matters in that division (sections 5 and 6). The IAS pay rules place the Divisional Commissioner post at Level 14 in several states. For how these posts fit the whole service, see IAS ranks and hierarchy and what IAS officers do.

When you read about "the powers of a Collector", check which state's law it describes. The answer for Maharashtra need not hold for Punjab or Kerala.