Search by what you sell, in plain words, and get the HSN or SAC code with its usual GST rate. Every invoice line legally needs a code, and guessing one is how a rate ends up wrong for a whole year of billing.
It depends on last year's turnover:
E-invoicing is stricter than the turnover rule: the Invoice Registration Portal expects at least 6 digits and will reject a shorter code, so if you are anywhere near the e-invoicing threshold, use 6 from the start.
HSN codes describe goods: anything physical you hand over. They are an international system, so the first six digits mean the same thing in India as anywhere else.
SAC codes describe services and all begin with 99. Consultancy, job work, transport, software development, rent — these take a SAC, not an HSN.
If a single invoice mixes goods and services, each line carries its own code. That is normal and correct, not something to avoid.
Search by what the thing is, not by your trade name for it. "Chair" finds a code; "Executive Revolving Model X" does not. If two codes look equally right, read the chapter heading above each one — the chapters are ordered by material and then by use, and that is usually what separates them.
For a service, describe the work rather than the deliverable: "design" and "software development" sit in different SAC codes even when the invoice says the same thing.
The rate follows the code. Put the code on the product record rather than typing it per invoice, and every future invoice for that item is consistent — which matters because GSTR-1 now summarises your sales by HSN, and an item billed under two different codes shows up as two different lines that will not reconcile.
When a product genuinely straddles two codes, pick the more specific one and keep a note of why. Consistency defends itself far better in a scrutiny notice than a mix.
On B2B invoices, yes — four digits below ₹5 crore turnover and six above it. On B2C invoices below ₹5 crore it is optional, but including it costs nothing and keeps your records consistent.
HSN codes are for goods and SAC codes are for services. Every SAC begins with 99, which makes them easy to tell apart at a glance.
Yes, and that is normal. An HSN code describes a category, not a single product, so a whole range of similar items can sit under one code at the same rate.
If the rate you charged was right, it is usually a reporting error to correct in a later return. If the wrong code also meant the wrong rate, the shortfall becomes payable with interest, so it is worth fixing as soon as you spot it.