Apply for regularisation of unauthorised construction done by you 

2) if application is rejected demolish illegal construction don’t by you 

3) you can complain against neighbour if he has done illegal construction 

You can ask him to proceed with his complaint and at the same time you may inform him that you will also complain against him for his unapproved constructions.

Let the authorities visit the spot and assess the penalty for this after inspecting the property on spot, then you can decide either to challenge the same in court or to regularize the same after paying the penalty.

Typically, five per cent deviation in size from approved layout plan is permitted. If this limit is exceeded, but the deviations are still considered safe, authorities may levy a penalty and provide approval

you will have to apply for regularization by paying premium for deficiency in the open space, if such deficiency can be condoned in the first place, which is at the complete discretion of the Municipal Commissioner, whether or not to allow the same by recording his reasons either ways

Generally, once a building licence is granted by a local government-municipality or corporation-there is no inspection of any nature later on to ascertain if the prescribed setback norms are complied with. This is the practical situation. Your neighbour has easement rights only if your extended construction blocks his ventilation- light and air. He may be simply threatening you to extract some monetary compensation. 

As per the information available, a setback is the open space across the front, sides or rear of a plot between the building and the street alignment or boundary of the plot. The setback of the buildings depends on various factors such as road width, land use, height of the building, etc. The setback norms are prescribed by the Tamil Nadu Combined Development and Building Rules, 2019 (TNCDBR), which are applicable to the Chennai Metropolitan Area.

According to the web search results, if you have constructed your building with a deviation from the approved setback norms, you may face some consequences such as:

• Your building may be considered as an unauthorized construction and may be liable for demolition or regularization by paying a penalty.
• Your building may not get a completion certificate or an occupancy certificate from the competent authority, which may affect your property rights and transactions.
• Your building may not comply with the safety and sanitation requirements and may pose a risk to yourself and others.
• Your building may be challenged by your neighbours or other affected parties in the court or tribunal on the grounds of violation of rules, nuisance, encroachment, etc.

Some of the options that you may have to deal with this situation are as follows:

• You can apply for regularization of your building by paying a penalty and submitting the required documents to the competent authority. The regularization scheme is available for buildings constructed before July 1, 2007, with a maximum deviation of 50% from the setback norms.
• You can modify or demolish your building to comply with the setback norms and get a fresh approval from the competent authority. This may involve additional cost and time for you.
• You can negotiate with your neighbours and get their consent or no-objection certificate for your building deviation. This may help you to avoid any legal disputes or complaints from them.
• You can defend your building in the court or tribunal if any case is filed against you by your neighbours or other parties. You can produce evidence to prove that your building deviation is minor and does not affect anyone’s rights or interests. You can also cite any precedents or judgments that may support your case.

Dear client

Deviating from the approved setback requirements for your construction can potentially lead to legal issues. Here are some considerations for your situation:

Neighbor's Complaint: If your neighbor threatens to complain about the setback deviation, they may have a valid concern. Even if their own property doesn't adhere to the approved setback, this doesn't necessarily give you the right to deviate from the approved setbacks for your property.

Legal Consequences: Violating approved setback requirements can result in legal consequences, including orders to demolish or modify your construction to comply with the setback rules. Fines and penalties may also apply.

Permission from Neighbors: Having permission from some neighbors for the setback deviation may not be sufficient to override the approved regulations. The setback rules are typically set by local zoning and building codes, and compliance with these codes is usually mandatory.

Amendment or Variance: Depending on local regulations, you may be able to apply for an amendment or variance to the setback requirements, but this process can be lengthy and may not guarantee approval. Your lawyer can assist with this process if it's applicable.

Resolution with Neighbors: Consider discussing the matter with your neighbors and attempting to find an amicable resolution. If your neighbors are willing to accept the deviation or reach an agreement, it may help mitigate the issue.