Most small and medium businesses don't get GST wrong because the law is unclear — they get it wrong because nobody walks them through it end to end. Here is the complete picture: when registration becomes mandatory, how the process actually works, how monthly liability gets discharged, what ongoing compliance looks like, and whether the composition scheme is the right call for your business.
Ask ten small business owners when they need to register for GST, and you will likely get ten different answers — some think it is based on shop size, others on whether they issue bills, others simply register the moment someone tells them to. This confusion is not a failure of the business owner. GST registration sits at the intersection of turnover rules, business type, state classification, and a handful of special categories that override all of the above — and very little of this is explained in one place. This article covers the full picture: when registration is actually mandatory, what the process involves, how your monthly tax liability gets discharged once you are registered, what ongoing compliance looks like, and when the composition scheme is worth considering instead of the regular scheme.
When Registration Becomes Mandatory
The starting point is turnover, but the exact number depends on two things: whether you supply goods or services, and which state you operate in. For a business dealing purely in goods, in a normal-category state, registration becomes mandatory once aggregate turnover crosses Rs. 40 lakh in a financial year — provided the business does not also supply services, does not deal in ice cream, pan masala, or tobacco, and is not making intra-state supplies from one of a specified list of states where the lower threshold applies regardless of goods-only status. If any of those conditions is not met, the threshold drops to Rs. 20 lakh. For service providers, the threshold is Rs. 20 lakh in normal-category states, and Rs. 10 lakh in special-category states such as Manipur, Mizoram, Nagaland, and Tripura. A business supplying both goods and services is generally assessed against the lower, services-based threshold unless it specifically qualifies for the goods-only limit.
Turnover, however, is only half the picture. Certain categories of persons must register regardless of how small their turnover is. This includes anyone making inter-state taxable supplies, casual taxable persons, persons required to pay tax under reverse charge, e-commerce operators, suppliers who sell through e-commerce platforms and are subject to tax collection at source, agents supplying on behalf of another taxable person, and non-resident taxable persons. If your business falls into any of these categories, the turnover threshold simply does not apply — registration is compulsory from the first rupee of relevant supply.
One practical point that catches many businesses off guard: turnover is computed on an all-India, PAN-wide basis, not state by state and not branch by branch. If you operate in two states under the same PAN, turnover from both is added together for threshold purposes, even though you may end up needing separate GSTINs for each state.
How the Registration Process Actually Works
Registration is filed entirely online through Form GST REG-01, and there is no government fee for doing it yourself. The process has two parts. Part A requires PAN, mobile number, email ID, and the state of registration; once these are validated through OTP and the PAN database, a Temporary Reference Number, or TRN, is generated. Part B is where the substantive information goes in — constitution of business, principal place of business, details of authorised signatories, bank account particulars, nature of business activity, and Aadhaar authentication of the authorised signatory, along with scanned supporting documents such as PAN, address proof, and a photograph.
Once submitted, a low-risk applicant who completes Aadhaar authentication is typically approved within three to seven working days without any physical site visit. Applications flagged as higher risk — due to a PAN-Aadhaar mismatch, an unusual registered address, or other red flags in the department's risk parameters — are routed for physical verification, which can extend the timeline to fifteen or even thirty days. On approval, the registration certificate is issued in Form GST REG-06, containing your fifteen-digit GSTIN. A separate fast-track route exists for applicants whose monthly output tax liability is expected to remain below Rs. 2.5 lakh, allowing electronic approval within three working days under a simplified scheme introduced for exactly this category of small business — though this comes with its own conditions and is worth discussing with your advisor before opting in, since withdrawing from it later requires a formal filing and a minimum period of returns to have been filed first.
A detail many new registrants miss: bank account details must be added to the GST portal within thirty days of registration, or before the first GSTR-1 filing, whichever is earlier. Skipping this does not just invite a notice — the portal will actively block GSTR-1 filing until bank details are updated, and continued non-compliance can lead to suspension of the registration itself.
How GST Liability Is Actually Discharged
This is the part that confuses even businesses that have been registered for years. GST is not paid the way income tax is — there is no single annual payment. Every registered person maintains two electronic ledgers on the GST portal: the electronic cash ledger, which reflects tax actually deposited via challan, and the electronic credit ledger, which reflects input tax credit available from GST paid on purchases. When a return is filed, output tax liability is first set off against available input tax credit in the credit ledger, and only the shortfall — if any — is paid in cash. Certain liabilities, such as tax under reverse charge, must be paid entirely in cash and cannot be discharged using input tax credit at all.
For most regular taxpayers, this plays out through two returns each period. GSTR-1 captures outward supplies — essentially every invoice you have issued — and for monthly filers is due on the 11th of the following month. GSTR-3B is the summary return where the actual liability is computed, credit is claimed, and the net tax is paid; for monthly filers, it is due on the 20th. Filing GSTR-1 before GSTR-3B matters practically, since GSTR-1 data auto-populates parts of GSTR-3B and reduces manual entry errors. Input tax credit itself can only be claimed to the extent it appears in your auto-generated GSTR-2B statement, which is built from your suppliers' own GSTR-1 filings — meaning a supplier's delay or error in their filing can directly restrict your ability to claim credit, regardless of whether you actually paid GST to them.
Businesses with turnover up to Rs. 5 crore in the preceding financial year can opt into the QRMP scheme — Quarterly Return, Monthly Payment — which allows GSTR-1 and GSTR-3B to be filed quarterly instead of monthly, while tax for the first two months of the quarter is still paid monthly through a simple challan (Form PMT-06), with final reconciliation in the quarter's GSTR-3B. Under QRMP, GSTR-1 is due on the 13th of the month following the quarter, and GSTR-3B on the 22nd or 24th depending on the state of registration. QRMP substantially reduces the number of filings — from roughly twenty-four returns a year down to eight — without changing when tax actually needs to be paid, which is a distinction many small taxpayers do not fully appreciate until they miss a monthly payment while assuming quarterly filing meant quarterly payment too.
Missing a due date carries two separate costs that are often confused with each other: a late fee for filing the return late, generally Rs. 50 per day split between CGST and SGST, capped depending on turnover slab and return type, and interest under Section 50 at 18 percent per annum on any tax paid late, which accrues from the day after the due date regardless of when the return is eventually filed. Even where there are no transactions in a period, a nil return must still be filed — skipping it triggers late fees and can block subsequent filings.
The Composition Scheme — A Genuine Alternative for the Right Business
For a certain kind of small business, the regular scheme's monthly compliance cycle is disproportionate to the tax actually involved, and Section 10 of the CGST Act offers an alternative. Under the composition scheme, eligible taxpayers pay a flat percentage of turnover instead of computing GST invoice by invoice, and file only once a quarter rather than monthly. Traders and manufacturers pay 1 percent, restaurants not serving alcohol pay 5 percent, and eligible service providers pay 6 percent — but the trade-off is that composition dealers cannot claim input tax credit on their purchases, cannot make inter-state outward supplies, and cannot issue a tax invoice, only a bill of supply.
Eligibility is capped at aggregate turnover of Rs. 1.5 crore in general category states, Rs. 75 lakh in specified special category states, and a separate Rs. 50 lakh limit applies to the service-provider variant of the scheme. Opting in requires filing Form CMP-02 before the 31st of March preceding the financial year in which the scheme is to apply — the portal closes this window once the new financial year begins, so the decision has to be made in advance, not mid-year. Once in the scheme, compliance is genuinely lighter: a quarterly statement in Form CMP-08 by the 18th of the month following each quarter, where the tax itself is paid, and a single annual return in Form GSTR-4.
The commercial fit of this scheme depends almost entirely on who your customers are. A composition dealer selling to end consumers loses little, since those customers were never going to claim input tax credit anyway. A composition dealer selling to GST-registered businesses is a different story — those buyers cannot claim any credit on purchases from a composition dealer, which often makes composition-scheme suppliers commercially unattractive to B2B buyers regardless of price. This is the single most common reason a composition-eligible business should still choose the regular scheme: if your customer base is primarily other GST-registered businesses, the loss of their input tax credit will usually cost you more in lost business than the compliance savings are worth.
It is also worth knowing what happens if turnover crosses the composition threshold mid-year, since the exit is not optional at that point. The business must switch to the regular scheme, file Form CMP-04 to formally exit, and can then claim input tax credit on stock held as of the transition date by filing Form ITC-01 within sixty days. From that point, regular invoicing and monthly or QRMP filing obligations apply going forward.
Getting the Basics Right, Early
Most of the GST difficulties small and medium businesses face later — blocked credit, mismatched returns, notices referencing turnover the business did not realise it had crossed — trace back to decisions made incorrectly at the registration stage or in the first few months after. Whether registration is actually triggered yet, which scheme genuinely fits your customer base, and how to structure monthly compliance so liability is discharged correctly and on time are all questions worth settling with a clear head before a deadline or a notice forces the issue. If you are unsure where your business currently stands on any of this, it is worth having your specific turnover, customer mix, and current filings reviewed rather than extrapolating from a general rule of thumb.
This article summarises the general framework for GST registration and compliance as it currently stands and does not constitute advice for any specific business. Thresholds, forms, and due dates are subject to change by notification, and applicability should always be confirmed against your own facts.