GST Scrutiny Triggers: 15 Red Flags Every Business Must Fix to Avoid a Notice

15 GST Compliance Lapses That Frequently Trigger Departmental Scrutiny

Summary: The article explains that GST scrutiny is increasingly driven by comparison of data across GSTR-1, GSTR-3B, GSTR-2B, e-way bills, e-invoices, annual returns, books of account, financial statements and third-party data, and identifies 15 common compliance lapses that frequently trigger departmental scrutiny. These include non-reversal of input tax credit where supplier payments remain unpaid beyond 180 days, incorrect Rule 42/43 reversals, omission of incidental income, failure to examine GST on advances for services, reverse charge mechanism lapses, valuation issues in related-party and branch transactions, errors in GSTR-1, blocked ITC claims under Section 17(5), mismatches between GSTR-1 and GSTR-3B, ITC claims without GSTR-2B reconciliation, e-invoice and e-way bill mismatches, incorrect treatment of GST credit notes, stock, scrap and write-off discrepancies, wrong place of supply and tax type, and inadequate reconciliation between books, GST returns and annual filings. The article also provides preventive controls, reconciliation flows, monthly compliance checklists and documentation practices, and states that correct reporting, reconciliation and record maintenance form the basis of GST compliance and preparedness for departmental scrutiny.

Introduction

GST is a self-assessment law.

Every registered person files returns, claims ITC, pays tax, reports outward supplies and maintains records on his own. But the GST system is now highly data-driven. The Department compares GSTR-1, GSTR-3B, GSTR-2B, e-way bills, e-invoices, annual returns, books of accounts, financial statements and third-party data.

Many GST notices are not issued because the taxpayer intended to evade tax. They are often triggered because of small mistakes, wrong reporting, missing reconciliation or weak documentation.

A business may be compliant in intention, but still face scrutiny if its records do not speak clearly.

This article discusses 15 common GST compliance lapses which frequently invite departmental scrutiny.

1. Non-reversal of ITC where supplier payment is pending beyond 180 days

This is one of the most common audit points.

If a recipient has taken ITC on an invoice but has not paid the supplier the value of supply plus GST within 180 days from the invoice date, proportionate ITC is required to be reversed or paid with interest.

Once payment is later made to the supplier, ITC can be re-availed.

Issue	GST impact	Practical control
Supplier payment pending beyond 180 days	Proportionate ITC reversal/payment	Maintain vendor ageing invoice-wise
Part payment made	Proportionate reversal for unpaid portion	Link payments with invoices
Payment made later	ITC can be re-availed	Keep payment proof and reconciliation
RCM invoices	180-day rule does not apply	Separate RCM vendor ledger

2. Incorrect ITC on exempt supplies without Rule 42/43 reversal

Where inputs, input services or capital goods are used for both taxable and exempt supplies, full ITC cannot be retained.

Common credit has to be reversed proportionately.

Rule 42 applies to inputs and input services. Rule 43 applies to capital goods.

Type of credit	Relevant rule	Common mistake
Inputs	Rule 42	Full ITC claimed despite exempt turnover
Input services	Rule 42	Common office expenses not reversed
Capital goods	Rule 43	Capital asset used for taxable and exempt activity but no reversal
Non-business use	Rule 42/43	No proportionate reversal

Simple formula

Common ITC attributable to exempt supplies =

Common ITC × Exempt Turnover ÷ Total Turnover

Practical examples

Hospitals, educational institutions, banks, NBFCs, real estate businesses, charitable institutions and mixed-supply businesses should be very careful.

3. Omission of incidental income from GST reporting

Many businesses report only main sales.

But GST scrutiny also examines other income appearing in the profit and loss account.

These may include scrap sales, commission, incentives, recovery from employees, penalty income, cancellation charges, liquidated damages, packing charges, delivery charges, documentation charges and other recoveries.

Income appearing in books	GST question
Scrap sale	Is GST paid on sale of scrap?
Commission income	Is it taxable service?
Penalty / cancellation charges	Is it linked with supply or contract?
Packing / handling charges	Included in value of supply?
Recovery from customer	Reimbursement or taxable recovery?
Sale of old assets	Is GST paid on disposal?
Forex gain	Is it merely exchange fluctuation or linked with taxable supply?

Professional point

The Department does not look only at sales ledger.

It also looks at:

Profit & Loss Account

↓

Other Income

↓

Ledger Scrutiny

↓

GST Taxability Check

↓

Mismatch with GSTR-1 / GSTR-3B

↓

Notice / Audit Query

4. Failure to pay GST on taxable advances, especially for services

For goods, tax on advances has been largely relaxed for normal registered suppliers.

But for services, advances continue to be sensitive.

If advance is received for taxable services, GST implications must be examined at the time of receipt, unless a specific exception applies.

Type of advance	GST attention required
Advance for goods	Generally relaxed for normal registered suppliers
Advance for services	GST may be payable at receipt stage
Mobilisation advance	Common in works contracts and service contracts
Retention adjustment	Check time of supply and invoice terms
Security deposit	Not taxable unless adjusted as consideration
Advance later refunded	Proper refund voucher / credit note treatment required

Common lapse

Businesses record advance in balance sheet but forget to examine GST liability.

5. Ignoring Reverse Charge Mechanism on applicable expenses

RCM is a frequent departmental audit area.

Expenses are checked from the profit and loss account. If the expenditure is of a nature covered under reverse charge, GST has to be paid by the recipient.

Expense head	Possible RCM exposure
GTA freight	Check GTA option, invoice and rate
Legal fees from advocate	Generally RCM for business entity
Import of services	RCM under IGST
Director sitting fees / commission	RCM exposure
Security services	Check supplier and recipient category
Sponsorship	RCM in specified cases
Rent from Government / local authority	Check applicable notification
Services from unregistered persons in specified cases	Examine notified categories

RCM Control Flow

Expense booked

↓

Identify supplier status

↓

Check nature of service

↓

Check RCM notification

↓

Pay GST in cash under RCM

↓

Claim ITC, if otherwise eligible

6. Improper valuation in related-party or branch transactions

Transactions between related persons and distinct persons require careful valuation.

Branches with separate GST registrations are treated as distinct persons. Supply between branches may attract GST even without consideration in specified cases.

Transaction	GST risk
Branch transfer of goods	Taxable supply between distinct persons
Cross charge of common expenses	Valuation and documentation issue
Head office support to branch	Whether taxable service?
Related-party sale	Open market value / valuation rule check
Free supply to related person	Schedule I examination
Employee recovery from group entity	Taxability and valuation issue

Practical control

Maintain:

1. tax invoice,

2. valuation basis,

3. agreement / policy,

4. working papers,

5. recipient ITC position, and

6. branch-wise reconciliation.

7. Delay or error in filing GSTR-1

GSTR-1 is not a mere reporting form.

It creates the outward supply data for recipients. It affects their GSTR-2A/2B and ITC eligibility. Delay or wrong reporting in GSTR-1 can create notices for the supplier as well as commercial disputes with customers.

Lapse	Possible impact
GSTR-1 filed late	Late fee, notice, recipient ITC issue
Invoice missed	GSTR-1 vs books mismatch
Wrong GSTIN	Customer ITC blocked or delayed
Wrong place of supply	IGST vs CGST/SGST issue
Wrong tax rate	Short payment / excess payment issue
Wrong B2B/B2C classification	Data mismatch

Good practice

Before filing GSTR-1, reconcile it with:

Sales register

E-invoice data

E-way bill data

Debit notes

Credit notes

Books of accounts

8. Claiming blocked ITC under Section 17(5)

Section 17(5) is a favourite area in audits.

The taxpayer may feel that an expense is business-related. But GST law may still block ITC.

Common blocked ITC area	Typical example
Food and beverages	Staff meals, catering
Personal consumption	Personal-use expenses booked in business
Motor vehicles	Cars used by business, subject to exceptions
Club membership	Club / health / fitness membership
Works contract	Civil construction of immovable property
Goods lost / stolen / destroyed	Stock loss, fire loss, shortage
Gifts and free samples	Promotional free distribution
CSR and welfare expenses	Needs careful eligibility review

Simple test

Expense is in books

↓

GST charged by supplier

↓

Business use exists

↓

Still check Section 17(5)

↓

If blocked, do not claim ITC

9. Mismatch between GSTR-1 and GSTR-3B

This is one of the easiest mismatches for the system to detect.

If outward tax liability reported in GSTR-1 is higher than tax paid in GSTR-3B, the system may generate scrutiny.

Comparison	Departmental concern
GSTR-1 tax > GSTR-3B tax	Short payment of tax
GSTR-3B tax > GSTR-1 tax	Reporting error or missed invoice
Credit notes in GSTR-1 not adjusted properly	Wrong tax reduction
Amendments not tracked	Period-wise mismatch
Different taxable values	Possible suppression or classification error

Reconciliation flow

Books sales

↓

GSTR-1 outward supply

↓

GSTR-3B tax payment

↓

E-invoice data

↓

Annual return

↓

Difference explained with documents

10. Claiming ITC without reconciling GSTR-2B

ITC should not be claimed merely because invoice is available in books.

GSTR-2B reconciliation is now a key compliance control.

ITC issue	Scrutiny trigger
Invoice not appearing in GSTR-2B	ITC claimed without supplier reporting
Supplier GSTR-3B not filed	Rule 37A issue
Supplier registration cancelled	Genuineness verification
Wrong GSTIN used by supplier	Credit not appearing correctly
Credit note uploaded by supplier	ITC reversal required
Ineligible ITC shown in 2B	Wrong claim in 3B
Time-barred ITC	Section 16(4) issue

Minimum documents for ITC defence

Document	Purpose
Tax invoice	Basic ITC document
GSTR-2B	Supplier reporting support
Goods receipt note	Receipt of goods
Service completion proof	Receipt of service
E-way bill / transport document	Movement proof
Payment proof	Vendor payment trail
Ledger confirmation	Reconciliation support

11. E-invoice and e-way bill mismatch

E-invoicing and e-way bill data are strong audit tools.

Mismatch between invoice, e-invoice, e-way bill and return can create scrutiny.

Mismatch	Risk
E-invoice generated but not reported in GSTR-1	Outward supply omission
E-way bill generated but no invoice in returns	Possible unreported supply
Invoice value differs from e-way bill value	Valuation query
Wrong HSN / rate	Classification issue
Movement without proper e-way bill	Detention / penalty risk
Cancelled e-invoice but supply exists	Reporting error

Control

Every month, reconcile:

E-invoice portal

↓

E-way bill portal

↓

Sales register

↓

GSTR-1

↓

GSTR-3B

12. Incorrect treatment of credit notes and financial credit notes

Credit note under GST is not the same as a commercial adjustment note.

A GST credit note must satisfy Section 34 requirements. If time limit or conditions are not satisfied, tax liability may not reduce even if commercial credit is given to customer.

Situation	GST treatment
Goods returned within time	GST credit note may be issued
Rate or value wrongly charged	GST credit note may be issued
Post-supply discount as per prior agreement	Credit note possible if conditions are met
Pure financial adjustment	Does not automatically reduce GST liability
Credit note issued after time limit	Commercial effect may remain, GST adjustment may fail
Credit note issued by recipient	Not a GST credit note for supplier’s tax reduction

Practical warning

Do not reduce GST liability merely because the customer account has been credited.

13. Stock differences, scrap, shortages and write-offs

Stock is not only an accounting item. It is also a GST-sensitive item.

Departmental officers often compare purchase, production, sales, stock records, e-way bills and financial statements.

Stock issue	GST concern
Scrap generated but not sold/reported	Unreported outward supply
Stock shortage	Possible unaccounted sale
Goods destroyed	ITC reversal issue
Free samples	Blocked ITC / reversal
Gifts	Blocked ITC
Obsolete stock written off	ITC reversal examination
Job-work stock not returned	Deemed supply risk
Capital goods scrapped	GST on disposal / reversal check

Stock scrutiny flow

Opening stock

+ Purchases

+ Production

– Sales

– Consumption

– Wastage / scrap

= Closing stock

↓

Compare with books and GST records

14. Wrong place of supply and wrong tax type

Wrong place of supply can convert IGST into CGST/SGST or vice versa.

Even where total tax rate is same, wrong tax type can create litigation, interest, refund blockage and customer ITC issues.

Error	Impact
IGST charged instead of CGST/SGST	Wrong tax payment
CGST/SGST charged instead of IGST	Customer ITC dispute
Wrong shipping State	Place of supply mismatch
Bill-to / ship-to not analysed	Wrong reporting
Services classified under wrong POS rule	Tax paid in wrong State
Export treated as domestic or vice versa	Refund / liability issue

Professional control

For every transaction, ask:

What is supplied?

Who is supplier?

Who is recipient?

Where is movement ending?

Which POS rule applies?

Which tax is payable?

15. Poor reconciliation between books, returns and annual filings

GST compliance does not end with monthly returns.

Annual return and reconciliation statement bring together the full financial year. Differences between books, GSTR-1, GSTR-3B, GSTR-2B, e-way bill, e-invoice and financial statements invite scrutiny.

Reconciliation area	Why important
Books turnover vs GSTR-1	Outward supply reporting
GSTR-1 vs GSTR-3B	Tax payment verification
Books ITC vs GSTR-2B	ITC eligibility
GSTR-3B ITC vs GSTR-9	Annual consistency
Expense ledger vs RCM paid	Reverse charge compliance
Fixed asset register vs ITC	Blocked credit / disposal
Other income vs GST returns	Hidden supply check
Credit notes as per books vs GST returns	Tax adjustment check

Final audit formula

Books

+ GST returns

+ GSTR-2B

+ E-invoice

+ E-way bill

+ Annual return

+ Financial statements

= Complete GST compliance file

Summary Table — 15 GST Lapses and Preventive Action

No.	Compliance lapse	Main risk	Preventive action
1	180-day supplier payment not tracked	ITC reversal with interest	Vendor ageing review
2	No Rule 42/43 reversal	Excess ITC	Monthly exempt turnover working
3	Incidental income omitted	Short payment of GST	Other income GST review
4	GST on service advances missed	Tax and interest	Advance ledger review
5	RCM ignored	Tax, interest, penalty	Expense-wise RCM checklist
6	Related-party valuation wrong	Short tax payment	Valuation policy
7	GSTR-1 delayed/wrong	Notices and customer disputes	Pre-filing reconciliation
8	Blocked ITC claimed	ITC reversal	Section 17(5) checklist
9	GSTR-1 vs GSTR-3B mismatch	System scrutiny	Monthly liability reconciliation
10	ITC claimed without GSTR-2B match	ITC dispute	2B reconciliation
11	E-invoice/e-way bill mismatch	Reporting and movement risk	Portal-to-return matching
12	Wrong credit note treatment	Wrong tax reduction	Section 34 control
13	Stock/scrap/write-off issues	Unreported supply / ITC reversal	Stock GST review
14	Wrong place of supply	Wrong tax type	POS checklist
15	Poor annual reconciliation	Audit exposure	GSTR-9/9C working file

Master GST Compliance Flow Chart

Books of Accounts

↓

Identify outward supplies

↓

Check valuation, rate and place of supply

↓

Report correctly in GSTR-1

↓

Pay tax correctly in GSTR-3B

↓

Check ITC with GSTR-2B

↓

Reverse ineligible / common / 180-day ITC

↓

Pay RCM wherever applicable

↓

Reconcile with e-invoice and e-way bill

↓

Review annual return and financial statements

↓

Maintain documentation file

Practical Monthly GST Compliance Checklist

Area	Monthly question
Sales	Is every invoice reported in GSTR-1?
Tax payment	Does GSTR-3B match GSTR-1 and books?
ITC	Is ITC supported by GSTR-2B?
180-day condition	Are old unpaid vendors reviewed?
Exempt supplies	Is Rule 42/43 reversal done?
RCM	Are all RCM expenses identified?
Credit notes	Are GST credit notes within law and time?
E-invoice	Is e-invoice data matching returns?
E-way bill	Is goods movement matching sales?
Other income	Is GST impact examined?
Stock	Is scrap / shortage / write-off reviewed?
Branches	Are inter-branch supplies reported?
POS	Is correct tax type charged?
Blocked ITC	Is Section 17(5) reviewed?
Records	Are documents ready for audit?

Conclusion

GST scrutiny is increasingly based on data comparison.

The Department may not start with the allegation of tax evasion. It may start with a simple mismatch. But once a mismatch is noticed, the taxpayer must explain it with documents.

The best defence is not created after receiving a notice. It is created every month through correct reporting, proper reconciliation and strong documentation.

In GST, compliance is not merely return filing.

It is a complete discipline of:

• Correct classification
• Correct valuation
• Correct tax payment
• Correct ITC claim
• Correct reversal
• Correct reporting
• Correct records

A taxpayer who maintains this discipline can handle departmental scrutiny with confidence.

*****

Disclaimer: This article is meant for professional education and general awareness. GST law is subject to amendments, notifications, circulars, portal changes and factual interpretation. Readers should verify the applicable legal position before taking any business or litigation decision. The views expressed are personal and should not be treated as a legal opinion for any specific case without examining complete facts and documents.