GSTR-2B reconciliation for government contractors: TDS credit and ITC

Executing civil works, infrastructure projects, or maintenance contracts for government entities creates unique cash flow and tax compliance pressures. While running account bills face long payment cycles and retention money holdbacks, tax rules mandate strict monthly compliance. If your vendor invoices do not match GSTR-2B, input tax credit is blocked. At the same time, if the government department delays filing its TDS return, deducted funds remain locked away from your electronic cash ledger.

Separating inward ITC in GSTR-2B from Section 51 GST TDS

A frequent point of confusion among civil contractors is expecting department deductions to appear in GSTR-2B. Inward supply invoices and GST TDS run through completely distinct portal flows:

• Input tax credit on purchases and subcontracts: Governed by Section 16(2)(aa) of the CGST Act, credit for cement, steel, equipment hire, and subcontractor bills is admissible only if the supplier furnished the invoice in their GSTR-1 and it is communicated to you in auto-generated Form GSTR-2B. You can review how this matching operates in our GSTR-2B reconciliation and ITC matching guide.
• GST TDS deducted by departments: Under Section 51 of the CGST Act, notified government departments, local authorities, and public sector undertakings deduct tax at source on taxable supplies exceeding ₹2,50,000 under a contract. As specified under Rule 66 of the CGST Rules, the deductor furnishes Form GSTR-7 by the 10th of the succeeding month. This does not appear in GSTR-2B. Instead, it flows into TDS and TCS credit received on the GST portal.

Works contract ITC eligibility under Section 17(5)(c)

Works contract is defined under Section 2(119) of the CGST Act as a contract for building, construction, fabrication, erection, installation, repair, or renovation of immovable property wherein transfer of property in goods is involved. Contractors must handle two distinct input credit situations:

Under Section 17(5)(c) of the CGST Act, input tax credit is blocked on works contract services when supplied for construction of an immovable property, except where it is an input service for further supply of works contract service. Because a government contractor provides outward works contract services, subcontracted works contract services qualify under this exception.

For input materials such as cement, steel, fixtures, and consumables, the contractor uses them directly in fulfilling the contract. Every subcontractor bill and raw material invoice must be reconciled against GSTR-2B. If a subcontractor fails to upload their invoice in GSTR-1, or marks it with an incorrect GSTIN, Section 16(2)(aa) bars you from claiming ITC in GSTR-3B.

How to accept Section 51 TDS credit on the GST portal

To pull your deducted tax into the cash ledger, follow the official portal procedure detailed in the GST portal user guides:

1. Log into the GST portal and navigate to Services, Returns, Returns Dashboard.
2. Select the relevant financial year and return filing period, then click on TDS and TCS credit received.
3. Click Prepare Online. You will see Table 3 (TDS Credit Received) populated from GSTR-7 returns filed by government departments under Rule 66.
4. Review each record: verify the deductor GSTIN, gross invoice value, and deducted tax amount. Select Accept or Reject for each entry.
5. Click Compute Total, generate the summary, and proceed to file using DSC or EVC. Once filed, the accepted TDS amount is credited directly to your electronic cash ledger under Rule 87(9).

Worked example: month-end reconciliation for a government contractor

Consider Apex Infra Projects, a registered contractor executing a public works road project. In October 2026, the firm bills the state public works department, engages subcontractors, and buys materials.

1. Outward billing and TDS deduction:

• Taxable value of running account bill submitted: ₹10,00,000.
• Output GST charged at 18%: ₹1,80,000 (CGST ₹90,000 + SGST ₹90,000).
• Section 51 GST TDS deducted by the department at 2%: ₹20,000 (1% CGST ₹10,000 + 1% SGST ₹10,000).
• Net cash payment released by department: ₹11,60,000 (before income tax TDS and security deposits).

2. Inward supplies and GSTR-2B matching:

3. Tax settlement computation:

• Output tax payable: ₹1,80,000 (CGST ₹90,000 + SGST ₹90,000).
• Admissible ITC from GSTR-2B: ₹90,000 (₹54,000 + ₹36,000, split as CGST ₹45,000 + SGST ₹45,000).
• Gross liability payable in cash: ₹1,80,000 - ₹90,000 = ₹90,000 (CGST ₹45,000 + SGST ₹45,000).
• Section 51 TDS accepted on portal and credited to cash ledger: ₹20,000 (CGST ₹10,000 + SGST ₹10,000).
• Net fresh cash required to be deposited: ₹90,000 - ₹20,000 = ₹70,000 (CGST ₹35,000 + SGST ₹35,000).

Because Subcontractor B failed to upload invoice INV-109, ₹18,000 of input tax credit could not be availed in GSTR-3B for this period. Claiming it without GSTR-2B backing would risk discrepancy notices in Form GST ASMT-10 under scrutiny procedures governed by CBIC Instruction No. 02/2022-GST.

Managing delayed payments and the 180-day reversal rule

Government contractors regularly encounter billing disputes, measurement delays, and holdbacks. Inward bills from suppliers must be monitored closely for payment timelines:

• The 180-day rule: Under the second proviso to Section 16(2) of the CGST Act, if a contractor fails to pay a supplier within 180 days from the date of invoice, the input tax credit availed must be paid back with interest under Section 50. Even when government department payments are held up, this statutory clock against your vendor bills does not pause.
• Retention money and milestone billing: For outward supplies, tax invoices must be issued as per Section 31 before or at the time of milestone certification or payment release. Filing outward details under Section 37 in GSTR-1 establishes the liability that GSTR-7 deductor returns are reconciled against.

Frequently asked questions

Last checked: 26 October 2026. Sources: CBIC Tax Information Portal (CGST Act & Rules), GSTN Portal User Guides.