GST Invoicing and E-Way Bills: Tax Invoices, Delivery Challans, E-Invoicing, and Rule 138

In any indirect taxation system, the commercial invoice is the supreme evidentiary document. Under the Indian Goods and Services Tax (GST) framework, an invoice is far more than an accounting bill: it is the legal instrument that establishes the chargeability of tax, proves the movement of goods, and empowers the recipient to claim Input Tax Credit (ITC).

To prevent tax evasion and modernize the logistics corridor, the Government of India integrated digital verification directly into business workflows through two systems: the Electronic Way Bill (E-Way Bill) system and the Electronic Invoicing (E-Invoicing) system.

This guide examines the statutory rules governing GST documentation: the mandatory requirements of standard Tax Invoices, specialized instruments such as Bills of Supply and Delivery Challans, the accounting mechanics of Debit and Credit Notes, the end-to-end lifecycle of an E-Invoice via the Invoice Registration Portal (IRP), and the operational rules of E-Way Bill Rule 138.

1. The Standard GST Tax Invoice (Section 31)

Under Section 31 of the Central Goods and Services Tax (CGST) Act, 2017, every registered person making a taxable supply of goods or services must issue a Tax Invoice. The tax invoice serves two functions:

It creates an enforceable legal claim for payment against the buyer.
It acts as the statutory voucher without which a buyer cannot claim Input Tax Credit under Section 16.

flowchart TD
    TaxInvoice["Statutory Tax Invoice (Section 31)"]
    TaxInvoice --> Supplier["Supplier Identification<br/>• Name, Address, State Code<br/>• 15-Digit GSTIN"]
    TaxInvoice --> Serial["Document Metadata<br/>• Consecutive Serial Number (≤ 16 chars)<br/>• Date of Issuance"]
    TaxInvoice --> Recipient["Recipient Identification<br/>• B2B: Registered Name & GSTIN<br/>• B2C > ₹50,000: Full Address & State Code"]
    TaxInvoice --> ItemData["Goods / Services Specifics<br/>• Description of Goods / Services<br/>• HSN / SAC Code<br/>• Quantity, Unit & Total Value"]
    TaxInvoice --> TaxMath["Tax Calculations<br/>• Taxable Value (after discounts)<br/>• CGST, SGST, IGST Rates & Amounts<br/>• Place of Supply (with State Name)"]
    TaxInvoice --> Sign["Digital / Physical Signature<br/>• Authorized Signatory"]

The Unregistered Buyer Rule: Threshold of ₹50,000

In standard retail Business-to-Consumer (B2C) transactions, invoices often omit detailed customer addresses. However, GST law enforces a strict compliance threshold for high-value sales:

The Statutory Rule: Where a taxable supply is made to an unregistered recipient and the taxable value of the invoice equals or exceeds ₹50,000, the tax invoice must contain:

Name and address of the recipient.

Delivery address.

Destination State name and its corresponding 2-digit State Code.

Omitting these fields on an unregistered invoice over ₹50,000 invalidates the invoice and attracts statutory penalties.

2. Specialized Documentation: Alternatives to the Tax Invoice

Not every commercial transaction calls for a standard tax invoice. The law provides specialized instruments for specific business models and logistical circumstances:

graph TD
    Docs["Commercial Documentation Architecture"]
    Docs --> TaxInv["Tax Invoice<br/>(Taxable Supplies by Regular Taxpayers)"]
    Docs --> BoS["Bill of Supply<br/>(Composition Dealers & Exempt Goods)"]
    Docs --> AggInv["Aggregate Invoice<br/>(Daily Sales < ₹200 to Unregistered Buyers)"]
    Docs --> DelChal["Delivery Challan<br/>(Movement Without Immediate Sale / Triplicate)"]

1. Bill of Supply

A Bill of Supply is issued in place of a tax invoice when the supplier is legally prohibited from charging GST on outward transactions:

Who Must Issue It: Taxpayers registered under the Composition Scheme (Section 10) and suppliers dealing exclusively in wholly exempted goods or services.
Key Characteristics: A Bill of Supply contains no tax rates or tax amounts. The supplier cannot collect tax from the buyer, and the buyer cannot claim any Input Tax Credit.

2. Aggregate Invoice (Daily Summary Billing)

Retailers dealing in high-volume, low-value daily sales are relieved from generating individual paper invoices under strict conditions:

Criteria: The recipient is unregistered, and the value of the individual transaction is less than ₹200.
Execution: The seller issues cash slips to customers and prepares a single consolidated Aggregate Invoice at the close of each business day representing the total daily sum of all such micro-transactions.

3. Delivery Challan

When goods are transported between locations without an immediate commercial sale, the shipment cannot be accompanied by a tax invoice. Instead, Rule 55 prescribes the issuance of a Delivery Challan:

Typical Use Cases: Stock transfers between branches or warehouses; goods dispatched for job work; transportation of goods in Semi Knocked Down (SKD) or Completely Knocked Down (CKD) condition; and goods taken on exhibition or approval.
The Triplicate Requirement: In the event of a supply of goods, the Delivery Challan must be prepared in triplicate:
- Original Copy: Marked for the Consignee (Buyer/Recipient).
- Duplicate Copy: Marked for the Transporter (to accompany the shipment in transit).
- Triplicate Copy: Marked for the Consignor (Retained by the sender for accounting records).

3. Invoice Rectification: Debit Notes, Credit Notes, and Revised Invoices

Commercial realities—such as damaged shipments, pricing errors, or volume rebates—require adjustments to previously issued invoices.

flowchart LR
    OriginalInv["Original Tax Invoice Issued"]
    
    OriginalInv -->|Taxable Value Understated<br/>Tax Rate Understated<br/>Extra Goods Delivered| DebitNote["Debit Note (Sec 34(3))<br/>• Increases Buyer Debt<br/>• Increases Supplier Tax Liability"]
    
    OriginalInv -->|Goods Returned / Deficient<br/>Taxable Value Overstated<br/>Discount Allowed Post-Sale| CreditNote["Credit Note (Sec 34(1))<br/>• Decreases Buyer Debt<br/>• Reduces Supplier Tax Liability<br/>• Buyer MUST Reverse ITC"]

1. Debit Notes (Debit Memos)

A Debit Note is issued by the supplier when the original tax invoice understated the commercial reality:

Trigger Events: The supplier initially undercharged the taxable value; the supplier applied an incorrect lower tax rate; or extra quantities of goods were delivered.
Effect: Increases the debt obligation of the recipient and increases the outward tax liability of the supplier in their monthly return.

2. Credit Notes (Credit Memos)

A Credit Note is issued by the supplier to reduce the taxable value or tax amount declared on an earlier invoice:

Trigger Events: Goods are returned by the recipient; the services provided are found to be deficient; or post-sale discounts are granted.
Effect: Reduces the supplier’s outward tax liability. However, this tax reduction is permitted only if the recipient reverses their corresponding Input Tax Credit in their return.

3. Revised Tax Invoices

When an enterprise applies for GST registration within 30 days of crossing the turnover threshold, the effective date of registration relates back to the date they became liable. During the intervening processing period, the business may have issued provisional invoices without a GSTIN:

Statutory Window: Taxpayers must issue Revised Tax Invoices within one month from the date the Registration Certificate (Form GST REG-06) is issued to cover all transactions conducted during the interim period.

4. Statutory Timelines for Invoicing

Under Section 31, failing to issue an invoice within the statutory timeframe constitutes a regulatory offense:

Commercial Nature of Supply	Statutory Deadline for Invoice Issuance
Supply of Goods Involving Movement	On or before the date of removal of goods for delivery to the recipient.
Supply of Goods Not Involving Movement	On or before the date of delivery or making goods available to the recipient.
Continuous Supply of Goods	At or before the time each successive statement of accounts is issued or successive payment is received.
Standard Provision of Services	Within a statutory window of 30 days from the date of completion of service provision.
Banking and Financial Institutions / NBFCs	Extended statutory window of 45 days from the date of service provision.

5. The E-Invoicing System (IRP & IRN Workflow)

To standardize Business-to-Business (B2B) billing data and eliminate manual reconciliation discrepancies, India established the Electronic Invoicing (E-Invoicing) system:

Turnover Applicability: Mandated for all registered businesses whose aggregate turnover in any preceding financial year exceeds the statutory threshold (progressively transitioned from ₹50 Crores down to current regulatory thresholds).
Scope: Applies to B2B supplies, Business-to-Government (B2G) transactions, export invoices, and credit/debit notes.

sequenceDiagram
    autonumber
    participant ERP as Taxpayer ERP / Accounting Software
    participant IRP as Invoice Registration Portal (IRP)
    participant GSTN as GST Common Portal (GSTR-1)
    participant EWB as E-Way Bill Portal

    ERP->>ERP: Generate standard invoice JSON schema
    ERP->>IRP: Transmit invoice JSON via direct API / GSP
    IRP->>IRP: Validate syntax, verify duplicate entries & calculate hash
    IRP->>IRP: Generate 64-character Invoice Reference Number (IRN)
    IRP->>IRP: Apply digital signature & encode high-density QR code
    IRP-->>ERP: Return signed JSON with IRN & QR Code
    IRP->>GSTN: Auto-populate invoice data into Supplier GSTR-1
    IRP->>EWB: Auto-populate Part-A of E-Way Bill
    ERP-->>ERP: Print final invoice with QR Code for physical transit

Key Components of an E-Invoice:

Invoice Reference Number (IRN): A unique, 64-character alphanumeric hash generated using a secure SHA-256 algorithm based on the supplier’s GSTIN, invoice number, and financial year.
Digitally Signed QR Code: Contains essential invoice metadata (supplier and buyer GSTINs, invoice date, taxable value, tax split, and IRN) allowing road enforcement officers to scan and verify authenticity offline using handheld mobile scanners.

6. The E-Way Bill Architecture: Rule 138

An Electronic Way Bill (E-Way Bill) is a statutory electronic document mandated under Rule 138 of the CGST Rules for tracking the physical movement of consignments of goods across state and national highways.

flowchart TD
    EWB["E-Way Bill (Consignment Value > ₹50,000)"]
    
    EWB --> PartA["Part A (Consignment Information)<br/>• Supplier & Recipient GSTINs<br/>• Place of Delivery & Pin Code<br/>• Invoice / Challan Number & Date<br/>• Taxable Value of Goods<br/>• HSN Code (Min 4 Digits)<br/>• Transport Reason (Sale, Transfer, Job Work)"]
    
    EWB --> PartB["Part B (Transporter Information)<br/>• Motor Vehicle Registration Number<br/>• Transporter Document Number<br/>• Railway Receipt (RR) / Airway Bill / Lading No.<br/>• Vehicle Type (Regular vs Over Dimensional)"]

Core Operational Rules:

Consignment Threshold: Generation is mandatory prior to commencing movement whenever a consignment of goods has a value exceeding ₹50,000 (calculated on taxable value plus GST, excluding exempt supply value).
Two-Part Architecture:
- Part A: Captures the economic identity of the transaction (submitted by the consignor or consignee).
- Part B: Captures the logistics parameters (vehicle registration number or transporter docket details). An E-Way Bill is legally valid for movement only when Part B is completed.
The 15-Digit Transporter ID (TRANS ID): Small transporters who are not registered under GST because their turnover is below threshold limits cannot log in via GSTIN. To generate Part B or update vehicle numbers, they enroll on the E-Way Bill portal (ewaybillgst.gov.in) by submitting business and PAN credentials to receive a unique 15-digit Transporter ID (TRANS ID).

Statutory Exceptions: When is an E-Way Bill NOT Required?

Rule 138(14) specifies logistical situations where goods can be transported without generating an E-Way Bill, regardless of consignment value:

Non-Motorised Conveyance: When goods are transported using non-motorised transit modes (e.g., animal carts, handcarts, cycle rickshaws).
Customs Transit Corridors: Movement of goods under customs control from an international port, airport, or land customs station to an Inland Container Depot (ICD) or Container Freight Station (CFS) for customs clearance.
Statutorily Exempt Cargo: Transport of exempt goods (such as unbranded grains, fresh milk, vegetables), defense consignments, postal baggage, currency, and used personal household effects.

7. Key Takeaways & Operational Summary

Tax Invoices Support ITC Claims: A complete tax invoice is mandatory for charging tax and claiming input credits under Section 16.
₹50,000 Unregistered Buyer Threshold: B2C invoices equal to or exceeding ₹50,000 must include the recipient’s full address and destination state code.
Delivery Challans in Triplicate: Dispatched in triplicate when moving goods without an immediate sale (e.g., branch transfers or job work).
E-Invoicing Automation: Invoicing via the IRP generates a 64-character IRN and QR code while auto-populating GSTR-1 and E-Way bills.
E-Way Bill Compliance: Required for consignments exceeding ₹50,000, requiring both Part A (commercial data) and Part B (vehicle details) for lawful road transit.

8. Frequently Asked Questions (FAQ)

What is the difference between a Tax Invoice and a Bill of Supply?

A Tax Invoice is issued for taxable sales by standard registered taxpayers, details tax rates and amounts, and allows the recipient to claim ITC. A Bill of Supply is issued by composition taxpayers or for exempt supplies, contains no tax figures, and cannot be used to claim ITC.

Can an E-Way Bill be updated if a delivery truck breaks down during transit?

Yes. Under Rule 138(5), if a transport vehicle breaks down or cargo is transferred to a relief vehicle, the transporter or consignor can log into the portal and update Part B with the new vehicle registration number before continuing movement, preserving legal validity.

How does an E-Invoice differ from a standard digital PDF invoice?

A standard PDF invoice is an unstructured electronic document created by billing software. An E-Invoice is a standardized JSON document validated by the government’s Invoice Registration Portal (IRP), which issues an official digitally signed IRN and QR code before the bill is legally valid.

What is the validity period of an E-Way Bill?

Under Rule 138(10), for regular cargo, an E-Way Bill is valid for 1 day for every 200 kilometers of transit distance (or part thereof). For Over Dimensional Cargo (ODC) or multimodal transit involving ships, validity is calculated at 1 day for every 20 kilometers.