GST invoicing for online sellers: what is mandatory and what can be automatic

GST is the part of online selling nobody enjoys and everybody worries about. Sellers put off registration because it looks complicated, then panic when a marketplace or a customer asks for a proper tax invoice.

Here is the good news: the rules that apply to a small online seller are learnable in one sitting, and the boring repetitive part (making a correct invoice for every single order) is exactly the part software can do for you.

One thing before we start, and we mean it: this article is general education, not legal or tax advice. GST rules change, and your situation has details we cannot see. Please confirm anything that affects your business with a chartered accountant.

When do you actually need GST registration?

Three situations cover most online sellers.

1. Your turnover crosses the threshold. GST registration becomes mandatory once your annual turnover crosses a limit set by law. The commonly cited figures are Rs 40 lakh for goods and Rs 20 lakh for services in most states, with lower limits (Rs 20 lakh and Rs 10 lakh) in certain special category states. These numbers have changed before and could change again, so treat them as the general shape of the rule and check the current limits with your CA.

2. You sell interstate. Selling goods to customers in other states can trigger mandatory registration regardless of turnover. There have been relaxations over the years for certain categories of sellers, so the honest answer is: if you ship outside your state, sit with a CA before assuming you are exempt. For an online seller shipping across India, this is usually the rule that matters first, long before the turnover threshold.

3. You sell through a marketplace that collects TCS. Large ecommerce operators are required to collect tax at source, and most sellers on such platforms need GST registration to sell there at all. There is a narrow exemption for small, intrastate-only sellers of goods using a special enrolment number, but it does not cover interstate sales or services. If you sell through your own website and WhatsApp only, this particular rule works differently. Again: CA.

If none of the three apply to you yet, you may not need registration today. But note the word "yet". Growing sellers cross these lines earlier than they expect, and registering late is far more painful than registering on time.

What a GST-compliant invoice must contain

Once registered, every taxable sale needs a proper tax invoice. The required contents are specific. A compliant invoice generally includes:

• Your details: legal name, address, and GSTIN.
• Invoice number and date: the number must be unique and follow a consecutive series for the financial year. You cannot just make numbers up per order.
• Customer details: name and address, and their GSTIN if they are a registered business buying from you.
• Place of supply: the state the goods are going to. This determines whether the tax is CGST plus SGST (same state) or IGST (interstate), which is the single most common thing sellers get wrong.
• Item details: description, HSN code (the classification code for your product category), quantity, and unit.
• Values: taxable value, the tax rate applied, and the tax amount, shown separately for CGST, SGST, or IGST as applicable.
• Signature: physical or digital, per the rules that apply to you.

Small-value relaxations and consolidated invoices exist for certain cases, but if a customer asks for an invoice, you must be able to produce a correct one.

The mistakes we see sellers make again and again

Treating a payment screenshot as an invoice. A UPI confirmation proves money moved. It is not a tax document. If you are registered, every taxable sale needs an invoice whether or not the customer asked.

Charging CGST+SGST on an interstate order. The customer is in another state, the invoice should show IGST, but the template was set up once for local sales and never touched again. This creates filing mismatches that surface months later.

Broken invoice numbering. Handwritten or ad-hoc numbers with gaps, repeats, or a fresh "001" whenever a new notebook starts. Your invoice series is part of your filings; gaps invite questions.

Wrong or missing HSN codes. Sellers copy a code from a similar-looking product online and move on. The wrong code can mean the wrong tax rate, which means you collected the wrong amount from every customer.

Forgetting that shipping charges are usually taxable too. If you charge the customer Rs 60 for delivery, that charge generally attracts GST as part of the supply. Many sellers invoice the product and quietly ignore the shipping line.

No records at filing time. Orders scattered across chats, screenshots, and memory. Your CA then spends billable hours reconstructing what software should have recorded automatically.

None of these mistakes come from dishonesty. They come from doing a repetitive, detail-heavy task by hand, at 11 pm, after packing orders all day.

What automation can safely take over

Here is the useful way to split the work. Decisions stay with you and your CA. Repetition goes to software.

You and your CA decide:

• Whether and when to register.
• Which HSN codes and tax rates apply to your products.
• Your filing schedule and any scheme choices (composition vs regular, for example).

Software can then reliably do, for every single order, without you thinking about it:

• Generate a complete invoice with your GSTIN, the customer's details, and every required field.
• Maintain a clean, consecutive invoice number series.
• Detect the place of supply from the shipping address and apply CGST+SGST or IGST correctly, every time.
• Apply the tax rate you configured per product, including on shipping charges.
• Keep every invoice stored and exportable, so filing season is a download, not an archaeology project.

This is the honest boundary. Software should not choose your tax rate or tell you whether to register. It should make sure that once those decisions are made, no 11 pm order ever gets a wrong or missing invoice again.

Where KiEo fits

KiEo builds your online store from a conversation, and GST invoicing is built into the order flow. You set up your GSTIN and product tax details once (with your CA's guidance), and every order after that gets a compliant invoice automatically: correct fields, correct tax split by place of supply, clean numbering, all stored with the order. You can see your store, invoices included, before you pay anything.

Frequently asked questions

I sell only through WhatsApp and Instagram. Do I still need GST? The channel does not matter; the rules do. If you cross the turnover threshold, or sell interstate in a way that triggers mandatory registration, WhatsApp sales count exactly like website sales. Many small intra-state sellers below the threshold genuinely do not need registration yet. Confirm your case with a CA.

Can I just make invoices in a Word file or by hand? Legally, an invoice made by hand can be compliant if it contains every required field, follows a proper number series, and matches your filings. Practically, doing that correctly for hundreds of orders is where the mistakes in this article come from. Automation is not mandatory; it is just how you stop making manual errors.

What is the penalty for not registering or not invoicing? GST law provides penalties for failing to register when required and for incorrect or missing invoices, and they can be significant. We are deliberately not quoting figures because they depend on the case and change over time. The practical takeaway: register on time and invoice every sale, because fixing it later costs more than doing it right.

Do I charge GST to customers or absorb it in my price? Both are done. You can show tax as a separate line, or set a tax-inclusive price and let the invoice show the split. What you cannot do is collect GST from customers without being registered, or be registered and not account for tax on your sales. How you present pricing is a business choice; talk it through with your CA.