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An RO service bill needs to show which filters were replaced and whether the visit was under an AMC, because customers judge value by parts changed. Water filtering or purifying machinery and its parts fall under HSN 8421 at 18%, and repair and maintenance of household appliances under SAC 998715 at 18%. Beyond the basics, record the purifier model and serial number, input and output TDS readings, filters and membrane changed, AMC number and visit count, installation address and the next service due date.
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Or create these invoices in software, free| Description | HSN/SAC | Qty | Rate (₹) | Taxable (₹) | GST |
|---|---|---|---|---|---|
| RO+UV water purifier, 8 litre, wall-mounted, with installation | 8421 | 1 NOS | 12,500.00 | 12,500.00 | 18% |
| RO membrane 80 GPD, replacement | 8421 | 1 NOS | 1,800.00 | 1,800.00 | 18% |
| Sediment and carbon filter set | 8421 | 1 SET | 900.00 | 900.00 | 18% |
| Annual maintenance contract, 3 services, filters extra | 998715 | 1 YEAR | 1,500.00 | 1,500.00 | 18% |
| Service visit charge, non-AMC | 998715 | 1 VISIT | 350.00 | 350.00 | 18% |
| Taxable value | ₹17,050.00 | ||||
| GST (CGST + SGST, or IGST if inter-state) | ₹3,069.00 | ||||
| Invoice total | ₹20,119.00 | ||||
Sample prices are illustrative. Check the GST rate for your exact item or service before billing.
Rule 46 of the CGST Rules applies to every tax invoice, including this one:
Read more: HSN Codes and GST Rates for Electronics and Appliances · Billing for Service Businesses: Models, GST and Best Practice · What Is an HSN Code and Why Does Every GST Invoice Need One?
Heading 8421 covers filtering or purifying machinery and apparatus for liquids or gases, and is listed in the 18% schedule after 22 September 2025. A domestic RO purifier and its parts, such as membranes and filter cartridges designed for it, are classified with it. Pumps used in purifiers are generally classified under 8413 and adapters or SMPS units under 8504, both also at 18%, but use the supplier's HSN so your purchases and sales reconcile.
Annual maintenance plans are usually paid upfront for a year. Raise the invoice when the payment is received or the plan starts, at 18%. If the plan is comprehensive, filters replaced during visits are covered and need no separate invoice, although each visit should be recorded in a service report. If filters are extra, bill them at each visit with their HSN. Mixing the two models on one plan confuses customers and makes audits difficult.
Free installation bundled with a new purifier is part of the composite supply of the purifier at 18%. Extra fittings, such as a booster pump, extra pipe or a pre-filter, should be separate lines if charged. Where the business installs a purifier the customer bought online, the installation is a separate service, billed under the installation or repair codes at 18%.
During the manufacturer's warranty, authorised service partners replace parts free and bill the brand for labour. CBIC's Circular 195/07/2023 clarified that such free replacement parts are not a separate taxable supply to the customer. Independent service providers offering their own warranty on a repair should record free replacements against the original invoice.
Larger RO plants for offices, hotels and factories are still under 8421 but are often installed with civil work and piping. Where the plant becomes part of a building's water system under a single contract, take advice on whether the job is a works contract.
Many RO dealers also sell purifiers on marketplaces and then send technicians to install them. The online sale is invoiced by the dealer as seller, with the order ID, and the marketplace collects TCS on it. The installation visit that follows is part of that composite sale if it was promised in the listing price, so a second invoice should not be raised for it. Only paid add-ons requested at the visit, such as a booster pump, are billed afresh.
18%. Filtering and purifying machinery for liquids, heading 8421, is in the 18% schedule.
Filters and membranes designed for the purifier are classified with it under 8421 at 18%.
998715, maintenance and repair of electrical household appliances, at 18%.
Yes, if the customer pays the full year upfront. Issue the invoice at 18% when payment is received, and record each visit in a service report.
Raise one invoice per visit or per month to the society, listing each unit's flat or location, serial number and the parts replaced. If individual flat owners pay, bill them separately in their own names.
Sources: CBIC — Notification 9/2025-Integrated Tax (Rate), goods rate schedules · CBIC — Notification 9/2025-Central Tax (Rate), 17 Sep 2025 · CBIC tax information portal (notifications and SAC scheme) · GST Council — rate rationalisation press release, 56th meeting
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