Unique Quantity Code (UQC) in GST: What It Means, Full List & How to Stay Compliant

Filing GST returns involves far more than plugging in financial figures. Every line item in your return demands precise data reporting, including the units in which goods are measured. Here is where things go wrong for thousands of businesses every month: the GST portal does not understand “meters,” “kgs,” or “mtrs.” It only recognises standardised codes like MTR, KGS, and LTR.

This is the exact problem that the Unique Quantity Code, commonly searched as UQC in GST, was designed to solve. A UQC is a mandatory three-character code that defines the unit of measurement for goods and services across all GST documents. Whether you sell fabric by the metre or rice by the kilogram, the GST portal needs one universal language to validate your data.

The mismatch between what your accounting software calls a unit and what the portal actually accepts is one of the most common causes of JSON file rejections during GSTR-1 filing. A single wrong abbreviation can halt your entire upload and delay GST compliance.

This guide covers everything you need to know: the meaning and UQC full form in GST, why it matters for compliance, where exactly it appears in your filings, the complete official code list, common errors and how to fix them, and how to map units in your software for error-free e-way bill and e-invoice generation.

What’s UQC in GST?

So, what is UQC in GST? A Unique Quantity Code is a standardised three-character alphanumeric code used to measure the quantity of goods or services within the GST regime. For example, if you sell 50 kilograms of wheat, the unit “kilograms” is represented as KGS in your GST filings.

The UQC full form in GST is Unique Quantity Code (also referred to as Unit Quantity Code in some official references). Regardless of the variation, the purpose remains identical: replacing the many ways businesses write a unit with one standard code.

Before UQC, one taxpayer might report “meter,” another “mtr,” and a third simply “m.” This inconsistency made it nearly impossible for the government to aggregate or analyse trade data accurately. UQC eliminates this chaos by assigning a single code to each unit. The GST portal uses these codes to validate every return, ensuring complete uniformity across all taxpayers in India.

Think of UQC as a common language between your business and the GSTN system. Your internal records can use any shorthand you prefer, but when data flows into the GST ecosystem, only the official three-letter UQC is accepted. This standardisation applies to GSTR-1 uploads, e-invoice generation through the IRP, and e-way bill creation.

Why UQC Is Mandatory for Compliance

Understanding what is UQC in GST is one thing; understanding why it is non-negotiable is another. Here are the key reasons UQC is mandatory for every registered taxpayer:

• Data standardisation at scale: The government processes billions of line items across millions of returns. UQC ensures that every mention of “kilograms” is captured as KGS, enabling accurate trade analysis, policy decisions, and revenue forecasting.
• Eliminates ambiguity in tax assessments: Without standardised units, “10 boxes” and “10 pieces” could refer to vastly different quantities of the same product. UQC prevents such confusion, giving tax officers and automated systems a clear basis for assessment.
• Mandatory field in critical filings: UQC is a required field in the HSN summary (Table 12) of GSTR-1, the item details section of e-way bills, and the IRP schema for e-invoicing. If you are unfamiliar with how these filings work, refer to this guide to GSTR-1 filing for a detailed walkthrough.
• Instant JSON rejection for invalid codes: When you upload your return to the GST portal, the system validates every field against the official master list. An unsupported code like “kg” or “meter” triggers an immediate error, and your entire file is rejected. This is one of the most frequent reasons for filing delays.
• Audit trail integrity: Correct UQC usage creates a clean, verifiable audit trail. During GST audits or reconciliation exercises, consistent units make it straightforward to match invoices with returns.

For businesses generating e-way bills or complying with e-invoicing requirements, accurate UQC is not optional-it is the foundation of valid document generation.

Where You Need UQC in Your Filings

UQC in GST is not limited to a single form. Here is a checklist of every document and filing where a valid UQC must be present:

☑ GSTR-1 – Table 12 (HSN-wise Summary of Outward Supplies)This is the most common place where UQC errors surface. Table 12 requires the HSN code, description, quantity, UQC, and taxable value for every category of outward supply, including B2C transactions.

☑ E-Way BillsThe item details section of every e-way bill requires you to declare the quantity and its unit. The unit must be a valid UQC from the GST master list.

☑ E-Invoices (IRP Schema)E-invoicing mandates a valid UQC as part of the invoice registration payload submitted to the Invoice Registration Portal. Any mismatch results in schema validation failure.

☑ Tax InvoicesAs per CGST Rule 46, every tax invoice must mention the quantity and unit of goods supplied. While the physical invoice may display a descriptive term, backend reporting must use the official code.

☑ Credit Notes and Debit NotesWhenever you issue a credit or debit note referencing specific goods, the unit of measurement must align with the original invoice and use a valid UQC.

If you are unsure whether your invoices meet Rule 46 requirements, audit them against this checklist before your next filing cycle.

Official UQC Code List for GST

The GSTN maintains a master list of approved UQC codes. These are the only codes the portal will accept during validation. Below, the codes are categorised by measurement type so you can quickly find the one relevant to your business.

A critical rule: use OTH (Others) only when your specific unit genuinely does not appear on the official list. Overusing OTH when a valid code exists can attract scrutiny. The first three characters represent the code, and the accompanying text is the description.

You can verify codes against the official e-way bill master codes list maintained by GSTN.

Weight-Based Codes

Weight-based UQC codes are among the most commonly used, especially in manufacturing, agriculture, and commodity trading. KGS (Kilograms) is the default for most goods sold by weight. Use GMS (Grams) for items like spices or jewellery sold in smaller quantities. QTL (Quintal) and TON (Tonnes) are standard for bulk agricultural produce and industrial raw materials. MTS (Metric Ton) applies to heavy industries like steel and cement.

Codes Based on Volume

Volume-based codes apply to liquids, gases, and bulk chemicals. LTR (Litres) is the go-to for beverages, oils, and liquid chemicals. For pharmaceutical or cosmetic products measured in smaller volumes, use MLT (Millilitre). KLR (Kilolitre) suits large-scale water or fuel transactions. Note: 1 litre equals 0.001 KLR or 1000 MLT. Always confirm against the current master list, as some filing utilities may handle LTR differently. CBM (Cubic Meter) and CCM (Cubic Centimeter) cover gas and spatial volume measurements.

Codes for Length and Area

Length and area codes are essential for textiles, construction, and real estate. MTR (Meters) is the standard for fabrics and cables. CMS (Centimeters) works for smaller measurements. For area-based billing, SQM (Square Meters) is widely used in construction, while SQF (Square Feet) and SQY (Square Yards) suit real estate transactions. YDS (Yards) is common in the textile industry.

Codes for Count and Packaging

Count and packaging codes cover the broadest range of businesses. NOS (Numbers) and PCS (Pieces) are the most universal codes for items sold individually. DOZ (Dozen) applies to eggs, fasteners, and similar bulk-count products. Packaging-specific codes include BOX (Box), BTL (Bottles), CTN (Cartons), BAG (Bags), BDL (Bundles), PAC (Packs), and ROL (Rolls). Choosing between NOS and BOX depends on how you invoice: if you sell “1 box of 100 screws,” use BOX; if you sell “100 screws,” use NOS. Consistency across invoices and returns is critical.

UQC Errors You’ll Actually Run Into

Even experienced accountants encounter UQC-related errors. Here are the most common issues and how to resolve them:

Problem 1: “Invalid UQC Code” Error on the GST PortalThis is the most frequent error. It appears when the JSON file you upload contains a unit code that does not match the official master list. The portal rejects the entire file, not just the offending line item.

Why it happens: Your accounting software exported a free-text unit like “Kilogram” or an unsupported abbreviation. Solution: Open the JSON error report, identify the rejected line, and correct the unit to the exact three-letter code (e.g., KGS).

Problem 2: MTR vs “Meter” or “m”Many businesses type “Meter,” “metre,” or simply “m” in their invoicing software. The GST portal only accepts MTR. This single mismatch causes thousands of rejections monthly.

Solution: Update the unit in your software’s master settings to MTR. Do not rely on the description field.

Problem 3: KGS vs “KG” or “kg”Similar to the above, “KG” or “kg” is not a valid UQC. The correct code is KGS.

Solution: Search your item master for any unit labelled “KG” and remap it to KGS.

Problem 4: Misuse of OTH (Others)Using OTH when a valid code exists, or using it without a proper description, can cause compliance issues. The portal may accept it, but audits may flag unexplained OTH entries.

For a broader list of filing issues, check out this guide on common GST portal errors.

Fixing Invalid UQC Errors

If you have already encountered a rejection, follow these steps to resolve it quickly:

1. Download the JSON error report generated by the GST offline utility or the portal after a failed upload. This report identifies exactly which line items failed validation.
2. Locate the specific line item where the unit does not match the master list. The error message typically references the field name and the invalid value.
3. Update the unit in your accounting software to match the exact three-letter UQC. Go to your Unit Master or Item Master settings and correct the mapping.
4. Re-generate the JSON file from your software after saving the corrected mappings.
5. Upload again to the GST portal and verify that validation passes without errors.

This cycle takes minutes once you know where to look, but can save hours of back-and-forth with your tax consultant.

Mapping UQC in Your Accounting Software

The concept of UQC in GST becomes practical when you configure your accounting or ERP software correctly. The key process is called unit mapping: linking your internal inventory unit name to the official GST UQC.

Here is the typical workflow, regardless of which software you use:

1. Navigate to your Unit Master (sometimes called Unit of Measurement or UoM settings).
2. Select the unit you use internally (e.g., “No.”, “Kilo”, “Mtr”).
3. Map it to the official UQC from a dropdown list. Most GST-compliant software includes the full GSTN master list. Select “KGS” for your internal “Kilo,” “MTR” for your “Mtr,” and so on.
4. Save and validate. Generate a test report or JSON file and verify that the mapped UQC appears correctly in the output.

The important principle here is that you do not need to change your internal shorthand. Your warehouse team can continue using “No.” or “Pc” in daily operations. The mapping ensures that when data is exported for GST filing, the system automatically substitutes the correct three-letter code.

If you manage hundreds of SKUs, run a bulk audit of your item master. Export the list, filter by unit, and verify that every unit has a valid UQC mapping. This one-time exercise prevents recurring filing errors and is especially critical before quarterly or annual filing deadlines.

For businesses using multiple software systems (e.g., separate billing and inventory tools), ensure the UQC mapping is consistent across all platforms to avoid discrepancies in your GSTR-1 HSN summary.

How Razorpay Makes GST Invoicing Easier

Manually entering UQC codes for every invoice is tedious and error-prone, particularly for businesses processing hundreds of transactions monthly. This is where automation makes a tangible difference.

Razorpay Invoices is a fully GST-compliant billing solution designed to eliminate the friction of manual code entry. Here is how it helps:

• Automatic tax calculation: CGST, SGST, and IGST are calculated automatically based on your customer’s location, removing the guesswork from inter-state and intra-state transactions.
• Built-in compliant fields: Fields like UQC and HSN are integrated into the invoicing workflow. You select from valid options rather than typing free text, which eliminates the most common source of validation errors.
• Professional, branded invoices: Every invoice generated is formatted to meet GST compliance standards while reflecting your brand identity. These invoices are ready for filing without additional formatting.
• Reduced rejection risk: Because compliant fields are pre-validated, the chances of JSON rejection during GSTR-1 upload drop significantly.

For businesses looking to streamline GST compliance without overhauling their existing processes, Razorpay Invoices offers a practical, low-effort path to accurate, automated GST billing.

Conclusion

UQC in GST is a small detail that carries significant compliance weight. A single wrong code can reject your entire return upload, delay your filing, and potentially trigger notices. The solution is straightforward: use only the official three-letter codes from the GSTN master list, map them correctly in your software, and reserve OTH for genuinely unlisted units.

Review your unit mappings periodically, especially when adding new products or switching software. Consistent, accurate UQC usage is one of the simplest ways to ensure GST return accuracy and avoid unnecessary compliance headaches.

FAQs

1. What is the difference between UQC and SQC?

UQC (Unique Quantity Code) is used for GST returns and e-invoicing compliance within India, whereas SQC (Standard Unit Quantity Code) is used primarily for Customs declarations. For all domestic GST filings, always use the GST-prescribed UQC list (e.g., KGS, MTR).

2. What UQC code should I use for services in GSTR-1?

Services generally do not have a quantitative unit in the standard list. For the HSN summary in GSTR-1, you should typically use OTH (Others) or NA (Not Applicable) if your software and the specific schema version support it.

3. Can I amend a UQC error after filing GSTR-1?

Yes. If you filed with an incorrect UQC, you can amend the details in Table 9 (Amendments) of GSTR-1 in the subsequent tax period. However, you can only correct the line item details, not the GSTIN.

4. Is UQC mandatory for B2C invoices in the HSN summary?

Yes. The HSN summary (Table 12 of GSTR-1) requires a valid UQC for all supplies, including B2C. Even if the invoice shown to the customer does not explicitly display the code, backend reporting must use a valid three-letter UQC.

5. What happens if my specific unit is not in the UQC list?

If your unit (e.g., “Ream”) is missing from the official list, map it to the closest valid code or use OTH (Others) with a proper description. Do not manually type a custom code, as the portal will reject it during validation. Always verify against the official master codes list before filing.