Once businesses cross the e-invoicing threshold, two new terms suddenly become part of daily life: IRP and IRN. Most people hear these words from accountants or software pop-ups, but don’t really understand what they mean or why they matter.
This blog clears that confusion. We’ll explain what the Invoice Registration Portal is, what IRN actually does, and how the whole system fits into GST invoicing, without drowning you in technical language.
What Is the Invoice Registration Portal (IRP)?
The Invoice Registration Portal (IRP) is a government-authorised platform where invoice details are validated and registered for e-invoicing purposes.
Important clarification:
“IRP does not create your invoice. You still create invoices in your own billing or ERP software.”
The IRP’s job is to:
- Validate invoice data
- Generate a unique IRN
- Add a QR code
- Digitally sign the invoice
Only after this process does an invoice become a valid e-invoice under GST.
What Is IRN (Invoice Reference Number)?
IRN stands for Invoice Reference Number.
It is:
- A unique 64-character hash
- Generated for each invoice
- Based on supplier GSTIN, invoice number, and financial year
No two invoices can ever have the same IRN. This is what stops duplicate and fake invoices in GST.
Why IRP and IRN Were Introduced
Before e-invoicing:
- Fake invoices existed
- ITC fraud was common
- Invoice matching was messy
IRP and IRN were introduced to:
- Bring real-time invoice validation
- Eliminate duplicate invoices
- Improve ITC matching
- Reduce GST fraud
This system directly strengthens GST compliance.
How the IRP & IRN Process Works (Simple Flow)
Here’s the real-world process, step by step:
Step 1: Invoice Creation
Invoice is created in your accounting software (Tally, ERP, Zoho, etc.).
Step 2: Upload to IRP
Invoice data (JSON format) is uploaded to the Invoice Registration Portal.
Step 3: Validation by IRP
IRP checks:
- GSTINs
- Invoice number uniqueness
- HSN/SAC codes
- Tax calculations
Step 4: IRN Generation
If details are correct:
- IRN is generated
- QR code is added
- Invoice is digitally signed
Step 5: Auto-Sharing
The validated invoice is automatically shared with:
- GST portal (for GSTR-1)
- E-way bill system (if applicable)
Without IRN, Is an Invoice Valid?
No.
If e-invoicing applies to you and:
- IRN is not generated
- Invoice is issued directly to buyer
That invoice is invalid under GST law.
This can result in:
- Penalties
- ITC denial to buyer
- Audit objections
QR Code on IRP-Validated Invoice
Once IRN is generated, a QR code is attached.
It contains:
- Supplier GSTIN
- Recipient GSTIN
- Invoice number
- Invoice date
- IRN
- Invoice value
This allows instant verification during checks or audits.
Time Limit for IRN Generation
Best practice:
- Generate IRN before issuing invoice to buyer
Practically:
- IRN must be generated on the same day the invoice is issued
Delayed IRN generation can create compliance risks.
Cancellation of IRN
IRN can be cancelled only if:
- Cancellation is done within 24 hours on IRP
- Invoice is fully cancelled (no partial cancellation)
After 24 hours:
- IRN cannot be cancelled on IRP
- Changes must be adjusted through GST returns
This makes invoice accuracy extremely important.
Common IRP & IRN Mistakes Businesses Make
- Issuing invoice before IRN generation
- Wrong HSN or SAC codes
- Duplicate invoice numbers
- Trying to cancel IRN after 24 hours
- Uploading B2C invoices unnecessarily
Most IRP rejections are due to basic invoice errors, not system issues.
How IRP & IRN Connect With Other GST Rules
IRP does not work in isolation. It depends heavily on:
- Correct invoice structure
- Proper HSN/SAC classification
- Correct invoice timing rules
A mistake in any of these breaks the e-invoicing chain.
Recommended Reading
To fully understand IRP and IRN, these related guides will help:
- Start with basics in Understanding GST Tax Invoices: A Simple Beginner Guide to know why invoices are central to GST.
- For invoice timing, read GST Tax Invoice Rules for Goods: Time, Format & Cases and GST Tax Invoice Rules for Services: Time, Limits & Use.
- If your invoices are recurring, Continuous Supply Under GST: Goods vs Services Explained explains correct timing before IRN generation.
- To avoid IRP rejection due to missing details, read Mandatory Fields of GST Tax Invoice: Rule 46 Explained.
- For classification accuracy, HSN Code Rules Under GST: Meaning, Limits & Errors is critical.
- For overall understanding, E-Invoicing Under GST: Meaning, Rules & Step-by-Step ties everything together.
These blogs together create a complete GST e-invoicing knowledge base.
FAQs
1. What is IRP in GST?
IRP is the Invoice Registration Portal used to validate e-invoices and generate IRN.
2. What is IRN used for?
IRN uniquely identifies each e-invoice and prevents duplication.
3. Can IRN be edited once generated?
No. The invoice must be cancelled and reissued (within 24 hours).
4. Is IRN required for B2C invoices?
No. IRN applies only to e-invoicing transactions (mainly B2B).
5. Can multiple invoices be uploaded together?
Yes, via bulk upload or API integration.
6. What happens if IRN is not generated?
Invoice becomes invalid and may attract penalties and ITC issues.
