If you are preparing for a GST interview using a blog written in 2023, you are preparing to fail it.
Three things changed. The GST Council collapsed four rate slabs into two. GSTR-3B stopped being a return you could edit. And the Invoice Management System took over the decision of how much input tax credit you actually get. An interviewer who works in tax will know this within two questions.
This guide covers 40+ GST interview questions with model answers, organised from basic to advanced, and updated for the rules in force in 2026.
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What changed in GST — and what interviewers now ask
The rate structure was rebuilt
At its 56th meeting on 3 September 2025, the GST Council rationalised the four-tier rate structure into a two-rate system: a 5% merit rate and an 18% standard rate, with a special 40% de-merit rate for a narrow set of luxury and sin goods. The 12% and 28% slabs were abolished. The changes took effect from 22 September 2025.
A nil rate continues for exempt goods, and gold and silver remain at 3%. Individual health and life insurance policies became exempt.
If you answer "5, 12, 18 and 28 percent" to a question about GST slabs, the interview is effectively over.
One nuance worth knowing: invoices raised before 22 September 2025 are generally governed by the rates applicable when they were issued. The old slabs still show up in reconciliations and audits of earlier periods, so knowing them is useful — just don't present them as current.
GSTR-3B is no longer editable
Since the July 2025 tax period, the auto-populated outward tax liability in GSTR-3B has been hard-locked. Figures flowing in from GSTR-1, IFF and GSTR-1A cannot be edited directly in the return.
This changes the answer to a very common interview question. "How do you correct a mistake in GSTR-3B?" The correct answer is no longer "adjust it in the next month's 3B." It is: you correct it upstream, through GSTR-1A, before filing.
IMS now controls your input tax credit
The Invoice Management System governs ITC. Suppliers file GSTR-1, invoices land on your IMS dashboard, and you accept, reject or keep them pending. Your GSTR-2B is built from those actions.
The trap: taking no action is treated as deemed acceptance. An accountant who ignores IMS is silently accepting every invoice, including wrong ones.
The three-year time bar is live
Returns can no longer be filed once more than three years have passed from their original due date. This applies across GSTR-1, 3B, 4, 5, 6, 7, 8 and 9. Unreported liability and unclaimed ITC for those periods are permanently locked out.
What is coming next
The next phase of GSTR-3B hard-locking — auto-populating ITC in Table 4A directly from GSTR-2B, removing manual entry for B2B supplies — has been indicated for around July 2026. Confirm the current notified status on the GSTN portal before you quote a date in an interview. Saying "it has been signalled but check the latest advisory" is a stronger answer than stating a date that turns out to be wrong.
The 57th GST Council meeting is scheduled for 12 September 2026 in New Delhi, with registration simplification, input tax credit, corporate guarantees and small-business compliance relief on the agenda. If your interview is after that date, read the outcome.
Basic GST interview questions for freshers
Q1. What is GST?
GST is a destination-based, multi-stage indirect tax levied on the supply of goods and services across India. It replaced a fragmented set of central and state indirect taxes — excise duty, service tax, VAT, CST, entry tax and others — with a single tax, and allows credit of tax paid on inputs to flow through the chain so tax is effectively borne only by the final consumer.
What sets you apart: mention "destination-based" and explain it — the tax accrues to the state where the goods or services are consumed, not where they were produced.
Q2. What are the current GST slabs in India?
Following the 56th Council meeting, the structure is a merit rate of 5% and a standard rate of 18%, plus a special 40% rate for select luxury and sin goods such as tobacco, aerated drinks and high-end vehicles. A nil rate applies to exempt items, and gold and silver are taxed at 3%. The 12% and 28% slabs were removed with effect from 22 September 2025.
Q3. What are the types of GST?
CGST — collected by the Centre on intra-state supplies
SGST — collected by the State on intra-state supplies
UTGST — the union territory equivalent of SGST
IGST — collected by the Centre on inter-state supplies and imports, then apportioned to the destination state
Q4. What is the difference between CGST, SGST and IGST?
On an intra-state supply, the tax is split equally between CGST and SGST. On an inter-state supply, a single IGST is charged at the combined rate. A supply from Maharashtra to Maharashtra at 18% becomes 9% CGST plus 9% SGST. The same supply from Maharashtra to Gujarat becomes 18% IGST.
What sets you apart: explain the credit utilisation order. IGST credit must be exhausted first, against IGST, then CGST or SGST in any order. CGST credit cannot be set off against SGST liability, and vice versa.
Q5. What is the GST Council?
A constitutional body under Article 279A, chaired by the Union Finance Minister with state finance ministers as members. It recommends rates, exemptions, threshold limits and the model GST laws. The Centre holds one-third of the voting weight and the states together hold two-thirds, and a decision requires a three-fourths majority of members present and voting.
Q6. What is the threshold limit for GST registration?
For suppliers of goods, aggregate turnover of ₹40 lakh in a financial year, reduced to ₹20 lakh in special category states. For suppliers of services, ₹20 lakh, reduced to ₹10 lakh in special category states.
What sets you apart: note that turnover is computed on a PAN-India basis across all GSTINs under the same PAN, not state by state or branch by branch.
Q7. Who must register for GST regardless of turnover?
Persons making inter-state taxable supplies of goods, casual taxable persons, non-resident taxable persons, persons liable under reverse charge, e-commerce operators and those supplying through them, input service distributors, and agents supplying on behalf of another.
Q8. What is GSTIN?
A 15-character PAN-based registration number. The first two digits are the state code, the next ten are the PAN, the thirteenth is the entity number for that PAN within the state, the fourteenth is "Z" by default, and the fifteenth is a check digit.
Q9. What is aggregate turnover?
The total of all taxable supplies, exempt supplies, exports and inter-state supplies of persons with the same PAN, computed on an all-India basis. It excludes CGST, SGST, UTGST, IGST and cess, and excludes inward supplies on which tax is paid under reverse charge.
Q10. What are HSN and SAC codes?
HSN is the Harmonised System of Nomenclature used to classify goods; SAC is the Services Accounting Code used for services. Correct classification determines the applicable rate. With the move to a two-rate structure, businesses had to update HSN and rate masters in their ERP systems — misclassification now attracts demands and penalties.
Q11. What is the composition scheme?
A simplified option under Section 10 for small taxpayers who pay a flat percentage of turnover instead of regular slab-wise GST. Limits are ₹1.5 crore for traders, manufacturers and restaurants not serving alcohol, ₹75 lakh in specified states, and ₹50 lakh for service providers under Section 10(2A). Rates are 1% for traders and manufacturers, 5% for restaurants and 6% for eligible service providers.
What sets you apart: state the trade-off clearly. A composition dealer cannot claim input tax credit, cannot make inter-state outward supplies, cannot collect tax from customers, and must issue a bill of supply rather than a tax invoice. Compliance drops to quarterly CMP-08 payments and an annual GSTR-4.
Q12. What is a casual taxable person?
Someone who occasionally supplies goods or services in a state where they have no fixed place of business — an exhibitor at a trade fair, for example. Registration is mandatory, must be obtained at least five days before commencing business, is valid for up to 90 days, and requires advance deposit of the estimated tax liability.
Q13. What is the difference between exempt, nil-rated, zero-rated and non-GST supplies?
Nil-rated: taxable supplies attracting a 0% rate
Exempt: supplies exempted by notification; no ITC available on related inputs
Zero-rated: exports and supplies to SEZ units and developers; ITC is available and refundable
Non-GST: outside GST altogether, such as alcohol for human consumption and specified petroleum products
What sets you apart: the ITC distinction is the whole point of the question. Exempt supplies block credit; zero-rated supplies preserve it.
Q14. What is a tax invoice, and when must it be issued?
For goods, on or before removal or delivery. For services, within 30 days of supply, extended to 45 days for banking and financial institutions and NBFCs. It must carry the supplier's and recipient's GSTIN, HSN or SAC, taxable value, rate, tax amount and place of supply.
Q15. What is the difference between a debit note and a credit note?
A supplier issues a credit note when the taxable value or tax charged in an invoice exceeds what was actually payable — a sales return, a discount, or an overcharge. A debit note is issued when it falls short. Credit notes reduce output liability only if the recipient reverses the corresponding credit, which is why they must be declared in the return period they relate to.
Input tax credit questions
Q16. What is input tax credit?
ITC is the credit a registered person takes for GST paid on inward supplies of goods or services used in the course or furtherance of business, which can be set off against output tax liability. It is the mechanism that prevents cascading — tax on tax — and makes GST a value-added tax rather than a turnover tax.
Q17. What are the conditions for claiming ITC?
Under Section 16(2), all of the following must be satisfied:
The recipient holds a valid tax invoice or debit note
The recipient has received the goods or services
The details of the invoice appear in the recipient's GSTR-2B (communicated via IMS)
The supplier has actually paid the tax to the government
The recipient has filed the relevant return
The recipient pays the supplier within 180 days of the invoice date, failing which the credit is reversed with interest
What sets you apart: mention the 180-day rule unprompted. Most candidates list the first four conditions and stop.
Q18. How does IMS decide the ITC you get?
Suppliers file GSTR-1. Their invoices appear on the recipient's IMS dashboard, where the recipient can accept, reject or keep each one pending. GSTR-2B is generated from those actions and feeds ITC in the return. Because inaction counts as deemed acceptance, a business that never opens IMS accepts everything by default, including invoices raised in error.
Q19. What happens if the ITC you claim exceeds your GSTR-2B?
Under the current validations, mismatched ITC blocks the return. The portal moved from post-facto flagging to real-time hard validation, so GSTR-3B filing can be stopped where the ITC claimed exceeds the auto-populated GSTR-2B balance, where the RCM ledger carries an uncleared negative balance, or where IMS ledger conditions remain unresolved.
Q20. What are blocked credits under Section 17(5)?
Credits not available even where the general conditions are met, including motor vehicles with seating capacity of up to 13 persons (with limited exceptions), food and beverages, outdoor catering, beauty treatment and health services, club and fitness centre memberships, works contract services for construction of immovable property other than plant and machinery, goods lost, stolen, destroyed or written off, and goods disposed of as gifts or free samples.
Q21. What is the difference between GSTR-2A and GSTR-2B?
GSTR-2A is a dynamic statement that keeps changing as suppliers file. GSTR-2B is a static, period-locked statement generated on a fixed date, and it is GSTR-2B — not 2A — that determines eligible ITC for the return.
Q22. How is common ITC apportioned between taxable and exempt supplies?
Under Rules 42 and 43, credit attributable to exempt supplies and non-business use must be reversed proportionately, based on the ratio of exempt turnover to total turnover, with an annual recomputation. Rule 42 deals with inputs and input services; Rule 43 deals with capital goods, spread over 60 months.
Q23. Can ITC be claimed on goods received in instalments?
Yes, but only on receipt of the last instalment.
Returns and compliance questions
Q24. What is the difference between GSTR-1 and GSTR-3B?
GSTR-1 is the statement of outward supplies, reported invoice by invoice. GSTR-3B is the summary return where liability is discharged, and credit is utilised. Since the July 2025 period, the outward liability in GSTR-3B is auto-populated from GSTR-1 and IFF and cannot be edited, which means GSTR-1 has become the return that actually determines your liability.
Q25. GSTR-3B is locked. How do you correct an error now?
Through GSTR-1A, the amendment facility that lets you correct outward supply details for a period before GSTR-3B for that period is filed. Once GSTR-3B is filed, remaining corrections move to amendment tables in a subsequent GSTR-1, subject to the applicable time limits.
What sets you apart: the practical consequence — the reconciliation work has shifted earlier in the month. You now check before filing GSTR-1, not after filing 3B.
Q26. What are the main GST returns?
GSTR-1 — outward supplies, monthly or quarterly under QRMP
GSTR-3B — summary return and tax payment
GSTR-2B — auto-generated statement of eligible ITC
GSTR-4 — annual return for composition taxpayers
GSTR-5 / 5A — non-resident taxable persons and OIDAR suppliers
GSTR-6 — input service distributors
GSTR-7 / 8 — TDS deductors and e-commerce operators
GSTR-9 / 9C — annual return and reconciliation statement
Q27. What is the QRMP scheme?
Quarterly Return, Monthly Payment — available to taxpayers with aggregate turnover up to ₹5 crore. They file GSTR-1 and GSTR-3B quarterly but pay tax monthly, and can upload B2B invoices in the first two months through the Invoice Furnishing Facility so their customers' credit is not delayed.
Q28. What is the three-year time bar?
Returns cannot be filed once more than three years have elapsed from their original due date, across GSTR-1, 3B, 4, 5, 6, 7, 8 and 9. Any unreported liability and unclaimed ITC for those periods becomes permanently unrecoverable.
Q29. What are the consequences of late filing?
Late fee under Section 47, capped based on turnover, with a reduced fee for nil returns. Interest at 18% per annum on tax paid late, and 24% where excess or undue ITC has been claimed. Continued non-filing blocks e-way bill generation and can lead to suspension of registration.
Q30. What is the annual return, and who files it?
GSTR-9, filed by regular taxpayers. GSTR-9C is a self-certified reconciliation statement between the annual return and the audited financial statements, required above the prescribed turnover threshold.
Q31. What is an e-way bill and when is it required?
An electronic document required for movement of goods where the consignment value exceeds ₹50,000, generated on the e-way bill portal before movement begins. Validity depends on distance. Some states apply lower thresholds for intra-state movement.
Q32. What is e-invoicing and who must comply?
Reporting B2B invoices, exports and SEZ supplies to the Invoice Registration Portal to obtain an IRN and a signed QR code. It applies to businesses whose aggregate annual turnover crossed ₹5 crore in any financial year from 2017-18 onwards, a threshold in force since 1 August 2023. Once crossed, the obligation is permanent even if turnover later falls.
What sets you apart: the 30-day reporting rule. Taxpayers with AATO of ₹10 crore and above must report invoices to the IRP within 30 days of the invoice date. Miss it and the IRP refuses the IRN, the invoice is not valid, and the recipient's credit fails.
Practical and scenario-based questions
These separate candidates who have worked on GST from candidates who have read about it. Expect them for accounts executive and above.
Q33. It is the 18th. Your supplier has not filed GSTR-1 and a ₹4 lakh invoice is missing from your GSTR-2B. What do you do?
You cannot claim the credit this period — the invoice is not in GSTR-2B, so a condition under Section 16(2) fails, and claiming it anyway risks the return being blocked at validation. Follow up with the supplier immediately, file GSTR-3B without the credit to avoid late fees and interest, and claim it in the period it appears. Escalate if the supplier is repeatedly late, and track it in a vendor compliance report, because credit lost past the time limit is not recoverable.
Q34. A customer in Karnataka was billed CGST and SGST instead of IGST. How do you fix it?
Issue a credit note against the incorrect invoice and raise a fresh invoice charging IGST, and report the amendment through GSTR-1A if GSTR-3B for the period has not yet been filed. The wrongly paid CGST and SGST can be handled under Section 77 read with Rule 89, which allows refund of tax paid under the wrong head without interest, provided the correct tax is paid.
Q35. Your ITC in GSTR-3B does not match GSTR-2B. Walk me through your process.
Pull the GSTR-2B for the period, reconcile it line by line against the purchase register, then classify the differences: invoices in the books but not in 2B (supplier has not filed), invoices in 2B but not in the books (missed entry, or an invoice that is not yours), amount or rate mismatches, and ineligible credits under Section 17(5) that must be excluded. Act on IMS accordingly, chase suppliers for the first category, and document the reconciliation. Never plug the gap by claiming the higher figure.
Q36. A vendor raises an invoice dated in March that reaches you in May. Which period do you claim it in?
The period in which it appears in GSTR-2B, subject to the outer time limit for availing credit for that financial year. If the supplier reported it late in the May GSTR-1, it appears in your May GSTR-2B and is claimed then — provided the annual cut-off has not passed.
Q37. Your company pays rent of ₹1,00,000 per month to an unregistered landlord. Any GST implications?
Renting of commercial property by an unregistered person to a registered person falls under reverse charge, so the tenant pays the GST directly and reports it as an RCM liability, then takes credit of the same, subject to the usual conditions. Check the current RCM notification list before answering in an interview, as the covered services are amended periodically.
Q38. You discover in September that ITC of ₹2 lakh was wrongly claimed in June. What now?
Reverse it in the current period's GSTR-3B and pay interest at 24% per annum from the date of utilisation. Voluntary correction before departmental detection avoids penalty. Where the amount is significant or relates to a closed period, DRC-03 is the route for voluntary payment.
Interview questions for experienced candidates
Q39. What is the reverse charge mechanism?
Where the liability to pay GST shifts from the supplier to the recipient. It applies to notified categories of goods and services — such as goods transport agency services, legal services from an advocate, sponsorship services and director's services — and to specified supplies from unregistered persons. The recipient pays the tax in cash, cannot use ITC to discharge the RCM liability, and can then claim credit of that tax if otherwise eligible.
Q40. What is place of supply, and why does it matter?
It determines whether a transaction is intra-state or inter-state, and therefore whether CGST and SGST or IGST applies, and which state receives the revenue. For goods it is generally the location where the movement terminates for delivery; for services it is generally the location of the recipient where registered, with specific rules for immovable property, events, transportation, banking, telecom and online services.
What sets you apart: a wrong place-of-supply determination is one of the most expensive errors in GST, because the tax cannot simply be re-characterised — it requires credit notes, fresh invoices and a refund claim under the wrong head.
Q41. How are exports treated under GST?
Exports are zero-rated. An exporter can either supply under a bond or Letter of Undertaking without paying IGST and claim a refund of accumulated input tax credit, or pay IGST on the export and claim a refund of the tax paid. The LUT route is more common because it avoids blocking working capital.
Q42. What is an inverted duty structure and how is it dealt with?
Where the rate on inputs is higher than the rate on outputs, causing credit to accumulate. Rule 89(5) allows a refund of the accumulated credit on inputs, subject to a prescribed formula, though not for input services and capital goods. The move to a two-rate structure was intended partly to reduce this problem in sectors like textiles.
Q43. How is value of supply determined?
Under Section 15, the transaction value is determined where the supplier and recipient are unrelated, and price is the sole consideration. It includes incidental expenses, taxes other than GST, and subsidies linked to price other than government subsidies. Discounts are excluded if given before or at the time of supply and shown on the invoice, or if given after supply under a pre-existing agreement linked to specific invoices with a corresponding ITC reversal by the recipient.
Q44. What is the appeal process under GST?
A first appeal lies to the Appellate Authority within three months of the order, with a pre-deposit of 10% of the disputed tax. A further appeal lies to the GST Appellate Tribunal, which is now operational, then to the High Court on substantial questions of law and to the Supreme Court.
Q45. What is the difference between Sections 73 and 74?
Section 73 applies where tax is not paid, short paid or wrongly refunded without fraud or wilful misstatement, with lower penalties and a shorter limitation period. Section 74 applies where there is fraud, wilful misstatement or suppression of facts, carrying a higher penalty and an extended limitation period.
How to prepare for a GST interview
Know the current numbers cold. Rates, registration thresholds, composition limits, due dates, e-invoicing threshold, interest rates. These are the questions where a wrong answer is unambiguous.
Understand mechanisms, not just definitions. Anyone can define input tax credit. Being able to trace what happens when a supplier files late, what IMS does with it, and how it lands in your GSTR-3B is what gets you hired.
Prepare three real examples from your own work. A reconciliation you cleaned up, a notice you responded to, a classification you corrected. Practical GST roles are filled on evidence of practical GST work.
Say "let me check the current notification" when you are unsure. In tax, an interviewer trusts a candidate who knows the rules change more than one who confidently quotes a repealed provision.
Practise saying the answers out loud. Knowing GST and explaining GST under pressure are different skills. Written preparation does not train the second one.
You can practise with a role-specific AI mock interview on BeSkill and get instant feedback on your answers — browse the Taxation interview library to find the one matching the role you are applying for.
Rates, thresholds and due dates change. Verify against the CBIC GST portal (cbic-gst.gov.in) and the GSTN advisories before relying on any figure. This article is for interview preparation and is not tax advice