In this guide — 6 sections
A Class 3 Digital Signature Certificate is the highest-assurance digital identity credential issued in India, requiring in-person or video verification against a government ID. TNOBPAS accepts only Class 3 for architect and licensed engineer submissions — and it is issued to an individual, never a firm. Without one, a building plan application cannot be submitted at all.
Sixth in the approval series, and the one that quietly gates every other article in it. The DSC is the reason ‘we handle the approval’ is not, on its own, an answer worth accepting.
What a Digital Signature Certificate is
A DSC is a cryptographic certificate issued by a licensed Certifying Authority under the Controller of Certifying Authorities, MeitY. It functions as the digital equivalent of a physical signature and seal, authenticating the signatory’s identity on electronic documents and portal submissions. DSCs are governed by the Information Technology Act, 2000 and the IT (Certifying Authorities) Rules, 2000.
Why the portal insists on it
Class 3 authentication serves three distinct purposes in the approval system, and they are worth separating because only the first is obvious:
- Professional accountability. With the DSC linked to a COA registration number, every submission carries the verified identity of a registered professional. If drawings contain errors or non-compliances, there is a named, credentialed individual accountable — not an anonymous draftsman.
- Submission integrity. The signature cryptographically seals the uploaded files. If any file is altered after signing, the signature becomes invalid and the portal's verification flags the tampering.
- Legal standing. Under the IT Act 2000, a document authenticated with a Class 3 DSC has the same legal standing as a physically signed one. That is what makes the approval order itself legally valid as an electronic document — no physical signature or stamp required.
The portal does not accept building plan submissions via username and password alone. The Class 3 USB token must be physically plugged in at the moment of submission authentication. Which means the architect has to be present — or remotely connected to a machine where their token is inserted — at the moment the application goes in. Filing is not something that can be delegated to an office assistant while the architect is travelling.
Class 1 Against Class 3
On Class 2, which you may still hear mentioned: the Controller of Certifying Authorities discontinued the category in January 2021. Existing Class 2 certificates remained valid until their natural expiry, and all renewals since are issued as Class 3. If anyone tells you their Class 2 certificate is fine for the portal, the certificate is by now several years past its own expiry window — the claim dates itself.
Who Can Hold One, and who can file
Six credentials, two questions
Can hold a DSC · Can file on TNOBPASCOA-registered architect
The primary credential for filing across all building categories. The COA registration number is linked to the TNOBPAS account.Licensed engineer, civil
May file for certain building types and sizes under TNCDBR 2019. A COA architect is required for all categories.Draftsman or CAD operator
No professional credential, so no TNOBPAS filing account regardless of DSC. Drawings they produce must be certified by a COA architect.Unregistered designer
Cannot file, and cannot legally certify drawings for building plan approval.Construction company
A firm cannot hold a DSC at all. It is issued to an individual — the architect employed or engaged by the firm holds it in their own name.Homeowner
Cannot file. You must appoint a COA-registered architect or licensed engineer to file on your behalf.A construction company that employs or engages an architect does not hold the DSC. The architect does. The firm name may appear as an organisation field on the certificate, but the credential is bound to one verified individual — which means if that architect leaves the firm, their DSC leaves with them.
So when a construction company says ‘we handle the approval’, that sentence describes a co-ordination arrangement, not a filing capability. Ask for the name and COA registration number of the specific architect who will be your TNOBPAS filing professional, and confirm that responsibility stays with them for the duration of the project.
Four Ways this stops your project
No valid DSC at all
The application simply cannot be submitted. Your project stalls at the pre-approval stage until a qualified architect with a valid Class 3 DSC is appointed.
Expired DSC
An architect whose certificate has lapsed cannot file until it is renewed. An architect who files regularly will not let this happen — one who files infrequently may not notice until the day it is needed.
Renewal: 3–7 working daysToken lost or damaged
The private key lives exclusively on the hardware token, so a lost or damaged token means the certificate must be reissued — a fresh application and full verification with the Certifying Authority.
Reissue: 5–10 working daysCOA registration lapsed
Even with a perfectly valid DSC, the portal verifies the architect’s COA number at submission. Registration requires annual renewal, and a lapsed one causes rejection regardless of the certificate.
Annual renewal requiredNotice that two of the four are calendar failures rather than competence failures. An expired certificate and a lapsed COA registration both belong to an architect who is perfectly qualified and simply has not renewed something. That is precisely why the verification questions below are worth asking a good architect as readily as a doubtful one — you are checking a date, not a reputation.
Ask for the Name and COA Number of the Person Who Will File
A firm cannot hold the credential. One individual will authenticate your submission — and you are entitled to know who, before you sign anything.
Five Questions before you appoint
- Ask for the COA registration numberEvery registered architect has one. The Council of Architecture maintains a public register searchable by name or number at coa.gov.in.
- Confirm the registration is currentCOA registration requires annual renewal. Ask them to confirm this year’s status or show the current certificate.
- Ask which Certifying Authority issued their DSCLicensed CAs include e-Mudhra, Sify and NSDL among others approved by CCA India. They should be able to name theirs and give you the validity period.
- Confirm the TNOBPAS account is activeAn architect who routinely files will have a current account with recent submissions they can point to.
- Request a reference from a recent filingAn application reference number from a recent submission is direct evidence of active filing capability — not a claim about it.
Four misconceptions worth clearing
- ‘My builder said they can handle the approval’ — a construction company cannot file. Only a COA-registered architect with a Class 3 DSC can. Ask for the COA number of the specific architect who will do it
- ‘The draftsman who drew the plans can submit them’ — a draftsman has no COA registration and cannot hold a filing account regardless of drawing skill or years of experience
- ‘The firm’s DSC can be used’ — certificates are issued to individuals. The firm name may appear as an organisation field, but the credential is bound to one person’s verified identity
- ‘A Class 2 DSC is still valid’ — discontinued in January 2021. Existing certificates were valid only to natural expiry, and every renewal since has been issued as Class 3
How submission actually works
Eight stages, and note where the token enters:
- Drawings and area statement completed — floor plans, elevations, sections, site plan, area statement ready for upload.
- Development charges computed and paid online from the area statement, via the portal gateway.
- Documents assembled and quality-checked — Patta, Sale Deed, Chitta, EC, approved layout plan, structural note, all current and consistent.
- USB token plugged in on submission day. The token is physically present at the machine, and its PIN authenticates the signing session.
- Application submitted — files uploaded, DSC authentication applied, and an application reference number generated.
- Receipt confirmed and the application enters the scrutiny queue.
- Query response via the same DSC if a deficiency notice is raised — the corrected submission is authenticated by the same certificate.
- Approval order issued digitally, downloaded by the architect and provided to you as a certified copy.
Step seven is the one worth planning around. Query responses use the same certificate as the original filing — so an architect whose DSC expires mid-process cannot answer a deficiency notice on your application either. A certificate that is valid on submission day but expires six weeks later can still strand a live application, since scrutiny alone routinely runs longer than that.
Pre-appointment checklist
Swipe or scroll to see the full table →
| Check | Before appointing anyone |
|---|---|
| COA registration number confirmed and verified on coa.gov.in by name or number | |
| Registration is for the current year — annual renewal confirmed | |
| Class 3 DSC confirmed valid and current — ask the CA name and expiry date | |
| Expiry date checked against your expected approval window, not just today’s date | |
| TNOBPAS account confirmed active with recent filing history | |
| At least one filing completed with your authority for a similar project type | |
| DSC issued in the architect’s individual name, not the firm’s | |
| Application reference number provided from a recent filing as verification | |
| Approval responsibility confirmed to stay with the named architect for the project duration |
A Certificate Valid Today Can Still Strand a Live Application
Query responses use the same certificate as the original filing — and scrutiny alone routinely runs longer than the gap people leave before renewal.
Verifying COA registration, DSC validity and filing history before signing the appointment letter eliminates the most common single point of failure in the approval process.
— Three questions, asked before the money moves
Frequently Asked Questions
What is a Class 3 DSC and why does my architect need one?
India’s highest-assurance digital signature, issued after in-person or video identity verification. Your architect needs it to file building plan applications on TNOBPAS. Without a valid one, they cannot authenticate submissions to CMDA, GCC or any Tamil Nadu government planning portal.
Who can use one for building plan approval?
Only COA-registered architects and licensed engineers can hold filing accounts and use a Class 3 DSC for approval. Draftsmen, unregistered designers, construction companies and homeowners cannot file. The certificate is issued to the individual professional, not the firm.
How does TNOBPAS use the DSC?
When an architect submits, their USB token must be physically present to authenticate the submission. The certificate cryptographically seals the uploaded documents and identifies the filing professional — so any subsequent alteration invalidates the signature and is flagged.
Can a builder file without an architect?
No. A construction company cannot file on TNOBPAS. Only a COA-registered architect or licensed engineer with a valid Class 3 DSC can. If a builder says they handle approval, ask for the COA registration number of the specific architect who will file for your project.
How do I verify my architect has a valid DSC?
Ask for their COA registration number and verify it at coa.gov.in; the name of the Certifying Authority that issued the DSC and its validity period; confirmation of an active TNOBPAS account with recent filing history; and an application reference number from a recent filing. An architect who files regularly will have all four readily available.
What happens if the DSC expires?
An expired certificate prevents the architect from filing or responding to deficiency notices. It must be renewed with the issuing Certifying Authority before any submission can proceed, which typically takes three to seven working days. Architects who file regularly renew proactively; those who file infrequently often do not notice until it is needed.
Is a Class 2 DSC still valid?
No. The Controller of Certifying Authorities discontinued Class 2 effective January 2021. Existing certificates remained valid only to their natural expiry, and all renewals since are issued as Class 3. The portal requires Class 3 for every architect and licensed engineer submission.
Can I submit my own application?
No. Homeowners cannot file directly. Only a COA-registered architect or licensed engineer with a valid Class 3 DSC and an active TNOBPAS account can — so you must appoint a qualified professional as your representative for the approval process.
What if my architect leaves the firm mid-project?
Their DSC leaves with them, because it is bound to their individual verified identity rather than to the firm. This is why it is worth confirming at appointment that approval responsibility stays with the named architect for the project duration — and knowing who that named architect is in the first place.
Does the architect need to be physically present to file?
The token does. The portal does not accept building plan submissions via username and password alone — the USB token must be plugged in at the machine used for submission, with its PIN authenticating the session. The architect must therefore be present, or remotely connected to a machine where the token is inserted.
Active Class 3 DSCs, Current COA Registration, Regular Filings
Named architects who file CMDA and GCC approvals routinely — with the registration number, the certificate validity and the recent filing references available before you ask.
A prerequisite, not a preference
The Class 3 DSC requirement is the mechanism that makes digital building plan approval professionally accountable — a named, verified individual behind every submission. Online plan submission is therefore not a service a firm provides in the abstract; it is something one credentialed person does, with a token in hand. Contact Buildiyo to discuss architectural and approval services.