GST TDS Under Section 51: Decoding the Gross Value vs. Taxable Value Confusion in GSTR-7 Filing

The Ground Reality: A Contractor's Nightmare

Consider Mr. Sharma, a works contractor based in Srinagar, who has been executing running-account bills for a government department over a span of three years. Every month, before the payment reaches his account, two percent is silently deducted from his bill amount. He proceeds on the reasonable assumption that this deduction represents his GST being appropriately handled, and files his own returns based on the invoices he has raised.

Then, out of nowhere, a scrutiny notice lands at his door. The department claims that the turnover declared in his returns falls short of the turnover that can be inferred from the Tax Deducted at Source entries recorded against him. He is asked to explain this "shortfall."

Mr. Sharma is genuinely confused — he has discharged GST on every rupee billed. What he may not immediately appreciate is that the discrepancy could have absolutely nothing to do with any error on his part. The root cause may simply be that the government office deducting his tax entered an incorrect figure in the wrong column of its own return.

This scenario is not theoretical. It is one of the most persistent and poorly understood sources of friction between government deductors, assessees, and tax officers under the GST TDS framework — and it has gained renewed significance following a structural change that took effect from September 2025.

Understanding GST TDS: The Legal Framework

What Is GST TDS and Who Must Deduct It?

Unlike ordinary registered businesses, government departments and certain specified entities are required to deduct tax at the point of payment to their suppliers — a mechanism known as Tax Deducted at Source under GST.

This obligation is governed by Section 51 of the CGST Act, 2017 (replicated under the JK GST Act, 2017). The provision reads, in its relevant part:

"(1) Notwithstanding anything to the contrary contained in this Act, the Government may mandate,—
(a) a department or establishment of the Central Government or State Government; or
(b) local authority; or
(c) Governmental agencies; or
(d) such persons or category of persons as may be notified by the Government on the recommendations of the Council,
('the deductor'), to deduct tax at the rate of one per cent. from the payment made or credited to the supplier ('the deductee') of taxable goods or services or both, where the total value of such supply, under a contract, exceeds two lakh and fifty thousand rupees."

How the TDS Rate Works in Practice

• For intra-State supplies: 1% under CGST + 1% under SGST = effective TDS of 2%
• For inter-State supplies: 2% under IGST = effective TDS of 2%

The ₹2.50 lakh threshold applies to the total contract value, not to each individual running bill. Therefore, a contract worth ₹9 lakh continues to attract TDS obligations even when a particular monthly bill is as small as ₹45,000.

The One Sentence That Changes Everything

Section 51 does not merely prescribe the rate of deduction — it also specifies, through an Explanation to sub-section (1), the precise base on which TDS must be computed:

"Explanation.— For the purpose of deduction of tax specified above, the value of supply shall be taken as the amount excluding the central tax, State tax, Union territory tax, integrated tax and cess indicated in the invoice."

This single statutory provision is the fulcrum around which virtually every genuine GST TDS dispute revolves. The law is clear and unambiguous: TDS must be calculated on the taxable value — the pre-GST figure — and not on the gross, tax-inclusive invoice amount.

A Practical Illustration

The difference of ₹4,320 per invoice may appear modest in isolation. However, aggregated across dozens of running-account bills over three years, and multiplied across hundreds of contractors dealing with the same deducting office, the cumulative impact on reconciliation and the resulting notices can be substantial.

Where the Problem Originates: The Data Entry Gap