A citizen can file a complaint about illegal construction or encroachment by approaching the local Municipal Corporation or Development Authority. The complaint can be submitted online through the official website or in person at the ward office, along with supporting documents like photos or property records. They can also file a grievance through helplines or public grievance portals like CPGRAMS (Centralized Public Grievance Redress and Monitoring System).

How to File a Complaint:
1. Gather Evidence
Take clear photos/videos of the illegal construction or encroachment.
Collect details like the exact address, landmark, and any visible violations (e.g., construction on public land, building beyond sanctioned plan, etc.).
Check local zoning laws or sanctioned building plans (available through your local municipal office or town planning department, if needed).

2. Identify the Relevant Authority
Depending on your city/town, the complaint should be submitted to one of the following:
Municipal Corporation / Urban Local Body
(e.g., MCD in Delhi, BMC in Mumbai, GHMC in Hyderabad)
Town Planning Department
Local Police (if there's a threat or obstruction)
Development Authority (like DDA, LDA, etc.)
Online Grievance Portal of your city/state

3. File the Complaint
You can submit a complaint in the following ways:
a) Online Complaint
Most municipalities have an online portal. Include:
Details of the complaint
Photos/evidence
Your contact details
Examples:
MCD Portal (Delhi)
BMC Portal (Mumbai)
GHMC (Hyderabad)

b) Written Complaint
Address it to the Commissioner or Zonal Officer of the local municipal body. Include:
Subject: “Complaint Against Illegal Construction/Encroachment at [Location]”
Description of the issue
Photos or evidence
Your name and contact (can request anonymity)
c) RTI Application (Optional but useful)
You can also file an RTI to ask:
Whether the construction has approval
If action has been taken on your previous complaint

4. Escalate if No Action
If no action is taken within a reasonable time (2–4 weeks):
Write to the State Urban Development Ministry
Approach the State Human Rights Commission (if public inconvenience is involved)
File a Public Interest Litigation (PIL) in High Court

Filing a complaint about illegal construction or encroachment typically involves contacting your local municipal authority or urban development department. Here's a general guide to help you through the process:
Steps to File a Complaint
Identify the Appropriate Authority
Common authorities include:
Municipal Corporation or Municipality
Urban Development Authority
Local Land Records Office
Building or Town Planning Department
You can often find contact details on the official website of your city's municipal body.
Gather Evidence
Take clear photos or videos of the illegal construction or encroachment.
Note down the exact location (address, landmark, GPS coordinates if possible).
Record any relevant dates or timelines of the activity.
Collect witness statements, if any.
File the Complaint
Online: Many cities have a grievance redressal portal (e.g., Delhi's MCD Online, Mumbai's MCGM Portal).
Offline: Visit the municipal office and file a written complaint with the building/planning department.
Include:
Your name and contact details (some systems allow anonymous complaints).
Detailed description of the issue.
Evidence (attachments if online).
Ask for an acknowledgment or complaint reference number.
Track the complaint online or follow up with the authority via phone or in person.
Additional Channels (India-specific examples)
State Helplines: Some states offer helpline numbers or mobile apps (e.g., Swachhata App, Public Grievance Portal).
RTI (Right to Information): If no action is taken, you can file an RTI to inquire about the status or action plan.
Legal Action: If authorities fail to act, consider approaching a local court or filing a PIL (Public Interest Litigation) in the High Court.