In this guide — 6 sections
Building plan approval is obtained from CMDA for the outer metropolitan area, GCC for city limits, or the applicable municipality or panchayat — by submitting drawings via the TNOBPAS portal. The application is filed by a COA-registered architect or licensed engineer using a Class 3 Digital Signature Certificate. Approval under TNCDBR 2019 is a legal prerequisite before any construction begins.
Building plan approval is not a formality. It is the document confirming your building complies with the FSI limits, setbacks, parking norms and height restrictions that apply to your plot — and without it the structure cannot be lawfully occupied, sold, or used as security for a construction loan.
TNCDBR 2019 — the Tamil Nadu Combined Development and Building Rules — is the unified regulation that replaced the previous fragmented rule sets with a single framework for all local bodies. It specifies FSI, setback distances, height limits, parking norms, rainwater harvesting requirements and accessibility standards for every building category across the state.
Which Authority covers your plot
Five authorities, one rulebookTNCDBR 2019 applies across all of them — what changes is the FSI, the parking norms and the timeline.
CMDA
TNCDBR 2019 + CMA Development RegulationsGCC
TNCDBR 2019 + GCC Building RulesMunicipality
TNCDBR 2019 + respective municipal rulesTown Panchayat
TNCDBR 2019; check local rulesDTCP
TN Town and Country Planning Act 1971 + TNCDBR 2019A plot in Sholinganallur may fall under CMDA, GCC or the Sholinganallur Municipality depending on its exact location — and the FSI and setback norms differ between them. Designing for CMDA FSI when the plot is under GCC jurisdiction, or the reverse, requires a complete design restart. Confirm the authority through the TNOBPAS portal or with a COA-registered architect before briefing, not after the first drawings arrive.
Documents: yours and the architect’s
Ownership and land documents — your responsibility
- Patta — current, in the applicant’s name. Confirms legal ownership and is mandatory for filing.
- Sale Deed — registered copy. Confirms acquisition, and is used for area computation in the area statement.
- Chitta or A-Register extract — current. Confirms survey number, extent and land classification.
- Encumbrance Certificate — last 15 years. Confirms no encumbrance or legal dispute on the plot.
- Approved layout plan, if the plot sits in one. Shows road width, open space designation and plot dimensions.
- Property tax receipt — latest. Confirms the property is in the applicant’s name with the local body.
Technical documents — prepared by the architect
- Form B — the application itself, in standard TNOBPAS format, filled and signed by the architect.
- Site plan at 1:400 or 1:200 — plot dimensions, road facing direction, setback distances from all boundaries, north point.
- Floor plans for all levels at 1:100 — dimensioned, with room names and usage, door and window positions, setback measurements.
- Elevations for all facades at 1:100 — building height, facade elements, parapet height.
- Section — at least one longitudinal, at 1:100 — floor-to-floor heights, staircase, total height.
- Area statement in tabular form — carpet area, built-up area and FSI-computed area per floor, confirming compliance with the maximum permitted FSI.
- Structural adequacy note — a brief signed statement from the structural engineer, required for G+2 and above in most authorities.
- Rainwater harvesting plan — mandatory under TNCDBR 2019 above the prescribed built-up area threshold.
Who Can File, and why it is absolute
Applications must be filed by a COA-registered architect or a licensed engineer for applicable building categories, holding a valid Class 3 Digital Signature Certificate. The DSC is issued to the individual rather than the firm, and authenticates the submission on TNOBPAS. The architect’s COA registration number is linked to their portal account, and every submission, amendment and query response carries their DSC authentication.
There is no workaround hereMost approval problems have a remedy. This one has none, and it is worth understanding why before appointing anyone.
An unlicensed designer or a layperson cannot file building plan approval on TNOBPAS under TNCDBR 2019. The Class 3 DSC for architectural practice is issued only to individuals by Certifying Authorities listed under the Information Technology Act, 2000.
This is why homeowners who engage unregistered designers discover their drawings cannot be filed at all — not that the process is harder, but that there is literally no mechanism to submit without a COA-registered architect’s Class 3 DSC. The drawings may be perfectly good. The portal will not accept them.
See how to verify COA registration — a free public check that takes about three minutes and settles this before any money changes hands.
Seven Stages on TNOBPAS
TNOBPAS — the Tamil Nadu Online Building Plan Approval System — is the state-wide digital platform for building plan applications, at tnobpas.tn.gov.in. All CMDA, GCC and most municipal applications are filed through it. The system handles online payment of development charges, document upload, query tracking and digital issuance of the approval order.
Seven stages on TNOBPAS
Two stages account for most of the clockDocument collection and soil testOwner
Gather Patta, Chitta, Sale Deed and EC; commission the soil test; brief the architect on site and design requirements.
Architectural and structural designArchitect
Concept plans, developed plans, then approval-format drawings — site plan, floor plans, elevations, sections, area statement. The structural engineer co-ordinates above G+1.
Development charge computationArchitect
Computed from published rates per sq.m of total built-up area. You review and confirm before payment.
TNOBPAS application filingArchitect
Log in with the Class 3 DSC; upload Form B, drawings and documents; pay the development charge online; the application reference number is generated.
Authority scrutinyAuthority
The plan checker reviews FSI compliance, setbacks, parking and area statement accuracy. Queries are raised through the portal where corrections are needed.
Query response, if raisedArchitect
The architect responds with revised drawings or clarification documents, uploaded via TNOBPAS. Each round is a separate cycle.
Approval order issuedAuthority
Issued digitally through TNOBPAS after final clearance. The architect downloads it and provides a certified copy. Validity is typically three years from the approval date.
Two stages carry most of the clock, and only one of them is anyone’s to hurry. Design at 3–6 weeks is yours and the architect’s; authority scrutiny at 30–60 working days is not. Every day saved has to be saved before filing — which is what makes the document checks in the next section worth more than they look.
Development charges are computed by the architect from the authority’s published rate per sq.m of total built-up area, and paid online at TNOBPAS before submission. The DC is computed from the area statement — so the area statement must be accurate before the computation happens. An inaccurate statement that understates built-up area may result in rejection or penalty. Review both the area statement and the DC computation with your architect before payment, not after.
A Plot in Sholinganallur Could Sit Under Any of Three Authorities
The FSI and setback norms differ between them, and designing to the wrong one means starting the drawings again from nothing.
Rejection Reasons, validity and renewal
Six common rejection reasons
- FSI exceedance — the area statement shows total built-up area above the maximum permitted for the plot. Requires redesign to reduce area before resubmission
- Setback non-compliance — one or more setback distances on the site plan fall below the minimum required under TNCDBR 2019 for the road width and plot size
- Road width inconsistency — the width shown does not match the actual road or the approved layout plan. Road width determines both the applicable FSI and the mandatory front setback, so an error here moves two things at once
- Rainwater harvesting absent — mandatory above the prescribed threshold. If the plan is missing or inadequately designed, the application is returned for correction
- Document mismatch — survey number in the Patta against the site plan, owner name in the Sale Deed against the Patta, plot dimensions in the approved layout against the site plan. Any inconsistency triggers a query or rejection
- Area statement computation error — errors in FSI-includable area, incorrect classification of covered areas, or missing inclusions and incorrect exclusions per the TNCDBR 2019 Schedule
Notice that four of the six are arithmetic or clerical rather than design failures. Road width, document consistency, area computation and the rainwater plan are all verifiable before filing by someone simply checking. Only FSI exceedance and setback non-compliance actually require the design to change — which means most rejections are avoidable at the desk rather than the drawing board.
Validity, renewal and lapse
Validity period
Approval under TNCDBR 2019 is typically valid for three years from the date of approval. Construction must commence and reach the approved stage within that period.
Renewal
If construction has not commenced or progressed sufficiently, you apply for an extension. Renewal is subject to the prevailing development charges and regulations at the time of renewal — which may differ from those at original approval.
Lapse
A lapsed approval requires a fresh application with current drawings and current development charge computation. All changes to TNCDBR 2019 or the development regulations issued in between apply to the new application.
Completion certificate
On completion, the owner or architect files Form C on TNOBPAS to confirm the building was constructed as approved. Required for permanent utility connections and the legal occupancy certificate.
The lapse card is the one that costs real money, and it is easy to miss. A renewal or fresh application is assessed against current rules — so any tightening of TNCDBR 2019 or the development regulations issued between your original approval and the renewal date applies to the new application. An approval allowed to lapse is not simply re-issued; it is re-decided.
Five tips for a faster approval
- Confirm jurisdiction and FSI firstBefore briefing the architect, using the TNOBPAS portal or the authority’s zoning map. Design to the confirmed FSI — do not assume it.
- Check document datesPatta, Chitta and EC must all be current. Applications with outdated documents are returned. Get them fresh before the architect begins.
- Resolve survey number discrepancies before filingIf the number in your Patta differs from the approved layout plan or the municipal record, resolve it through the Tahsildar’s office first. A survey number mismatch is the most common cause of avoidable delay.
- Commission the soil test in parallelIt does not affect the approval drawings unless an engineer’s note is required, but it is needed before construction. Running it alongside the approval process saves 2–4 weeks overall. See soil testing before construction.
- Engage a COA-registered architect from day oneThe approval process is their routine rather than a one-time challenge — and as section three establishes, there is no alternative route.
Pre-filing checklist
Swipe or scroll to see the full table →
| Check | Before TNOBPAS filing |
|---|---|
| Jurisdiction confirmed — CMDA, GCC, municipality, town panchayat or DTCP | |
| Applicable FSI confirmed for that authority, and the design drawn to it | |
| Patta current and in the applicant’s name | |
| Chitta or A-Register extract current | |
| Encumbrance Certificate covering 15 years obtained | |
| Survey number consistent across Patta, layout plan and municipal record | |
| Owner name consistent between Sale Deed and Patta | |
| Road width verified on site against the approved layout plan | |
| Area statement reviewed before development charge computation | |
| Development charge computation reviewed before payment | |
| Rainwater harvesting plan included with dimensions | |
| Structural adequacy note obtained for G+2 and above | |
| Architect’s COA registration and Class 3 DSC verified | |
| Soil test commissioned in parallel with the approval process |
Most Rejections Are Clerical, Not Design Failures
Road width, document consistency, area computation and the rainwater plan are all verifiable before filing — by someone simply checking them against each other.
The approval process is the architect's responsibility to execute. Providing accurate documents and a realistic timeline expectation is the homeowner's.
— Where the division of labour actually falls
Frequently Asked Questions
Is building plan approval mandatory before construction?
Yes — legally mandatory before any construction begins, under TNCDBR 2019 and the Tamil Nadu Town and Country Planning Act, 1971. Construction without it creates an unauthorised structure that cannot be legally occupied, sold or used as loan security. Regularisation is possible in some cases but involves penalties and is not guaranteed.
How long does approval take?
CMDA approval typically takes 60–90 working days from submission, assuming a complete and compliant application. GCC typically takes 45–70 working days. Applications that trigger queries need additional time for each round of corrections and resubmission — query rounds are the primary cause of delay.
What is TNOBPAS and how does it work?
The Tamil Nadu Online Building Plan Approval System is the state government’s digital platform for building plan applications. A COA-registered architect files the application, uploads documents and pays development charges through the portal using their Class 3 DSC. The authority reviews and issues queries or the approval order digitally through the same portal.
Who can submit an application?
Only a COA-registered architect or licensed engineer holding a valid Class 3 Digital Signature Certificate. An unregistered designer or the homeowner cannot file on TNOBPAS — the architect’s COA registration number is linked to their portal account and digitally authenticates each submission. There is no alternative route.
What is TNCDBR 2019?
The Tamil Nadu Combined Development and Building Rules, 2019 — the unified regulation specifying FSI, setback distances, height limits, parking norms, rainwater harvesting requirements and accessibility standards for all building categories across the state. It replaced the previous fragmented rule sets and is the primary legal reference for every application.
What documents are required?
From you: current Patta in the owner’s name, registered Sale Deed, Chitta or A-Register extract, a 15-year Encumbrance Certificate, the approved layout plan where applicable, and the latest property tax receipt. From the architect: Form B, site plan, floor plans, elevations, section, area statement, structural adequacy note and rainwater harvesting plan.
What is the validity of an approval?
Typically three years from the date of issue, within which construction must commence and progress. If it lapses, a fresh application with current drawings and current development charges is required — assessed against whatever the rules say at that point. A completion certificate on Form C must be filed on TNOBPAS after construction is complete.
Why do applications get rejected?
FSI exceedance in the area statement, setback non-compliance on the site plan, road width inconsistency, absent rainwater harvesting provision, document mismatch between Patta, Sale Deed and site plan, and area statement computation errors. Most are preventable with careful pre-filing review of the area statement and document consistency.
What happens if my approval lapses?
A lapsed approval requires a fresh application with current drawings and a current development charge computation. Any changes to TNCDBR 2019 or the development regulations issued between the original approval and the new application apply — so a lapsed approval is not simply re-issued, it is re-decided against the rules in force at that moment.
Can I speed up the process?
Only before filing. Confirm jurisdiction and FSI before briefing, get Patta, Chitta and EC fresh, resolve any survey number discrepancy through the Tahsildar’s office first, and run the soil test in parallel to save two to four weeks overall. Authority scrutiny itself runs to its own clock and cannot be accelerated.
Document Review, TNOBPAS Filing, Approval Order
COA-registered architects with Class 3 DSCs managing the complete CMDA and GCC process on your behalf — starting with the jurisdiction check that has to happen first.
Rewards preparation, penalises the incomplete
Building plan approval under TNCDBR 2019 is a structured process that rewards preparation and penalises incomplete submission. Understanding the correct TNOBPAS filing sequence and the most common rejection reasons lets you budget realistically for the timeline and avoid preventable delay. Contact Buildiyo for a free approval feasibility consultation.