Construction and property

GST invoice format for an aluminium windows and glazing contractor

An aluminium window or glazing contractor's GST invoice needs a window schedule: each opening's mark, width and height, area, section series, glass type and thickness, and hardware. Fixing windows and glass in a building is a works contract taxed at 18%, with glazing services under SAC 995471. Supplied without installation, aluminium doors and windows fall under HSN 7610, toughened or laminated safety glass under 7007 and float glass under 7005, all at 18%.

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Sample aluminium windows and glazing contractor invoice

Description	HSN/SAC	Qty	Rate (₹)	Taxable (₹)	GST
Aluminium sliding windows, powder-coated, with 5 mm clear glass, fixed at site (composite)	995471	38 SQM	5,600.00	2,12,800.00	18%
Toughened glass 10 mm partition with patch fittings, installed	995471	12 SQM	7,200.00	86,400.00	18%
Aluminium casement window frame, ex-works (no installation)	7610	4 NOS	9,800.00	39,200.00	18%
Toughened safety glass 8 mm, cut to size	7007	10 SQM	1,650.00	16,500.00	18%
Silicone weather sealant, 300 ml cartridge	3214	24 NOS	310.00	7,440.00	18%
Taxable value				₹3,62,340.00
GST (CGST + SGST, or IGST if inter-state)				₹65,221.20
Invoice total				₹4,27,561.20

Sample prices are illustrative. Check the GST rate for your exact item or service before billing.

Extra fields a aluminium windows and glazing contractor invoice needs

Window schedule with marks: Architects number every opening (W1, W2, SD1). A schedule with mark, size and quantity lets the site engineer check each window installed against the drawing before certifying the bill.
Section series and finish: Aluminium sections come in different series and powder-coat or anodised finishes. Naming the series and finish shows whether a premium system or an economy section was used.
Glass type and thickness: Clear float 5 mm, toughened 8 mm and laminated 6.38 mm differ greatly in cost and safety. Specifying glass per opening supports the price and the HSN used for separately supplied glass.
Hardware set: Handles, locks, rollers and friction stays decide how the window works. Listing hardware brand helps with warranty and replacement later.
Chargeable area rule: Many contractors charge a minimum area per window. Stating the rule on the invoice explains why a small ventilator is billed at the minimum.
Sealant and silicone specification: Weather sealing determines whether windows leak. Mentioning the silicone grade and whether it is structural or weather sealant documents what was used on the façade.

Standard GST invoice fields

Rule 46 of the CGST Rules applies to every tax invoice, including this one:

Supplier name, address and GSTIN
Consecutive invoice number (max 16 characters, unique for the year)
Date of issue
Customer name, address and GSTIN (if registered)
Place of supply with state name
HSN/SAC code per item
Description, quantity and unit
Taxable value after discounts
GST rate and CGST + SGST or IGST amounts
Signature or digital signature

GST rules that matter for a aluminium windows and glazing contractor

Glazing as building completion service

SAC 995471 covers glazing services, which include fixing glass panes, glass partitions and window glazing in buildings. When the contractor fabricates aluminium frames, supplies glass and installs them at site, the result is fixed to the building and the contract is a works contract taxed at 18% on the full value. A separate window-frame supply line without installation is a supply of goods under its own HSN.

Goods rates for frames and glass

Notification 9/2025-Central Tax (Rate) lists aluminium structures and parts of structures, including doors, windows and their frames, under 7610 in Schedule II at 18%. Safety glass of toughened or laminated glass under 7007 and float glass under 7005 are also at 18%, as are glass mirrors under 7009. uPVC windows are builders' ware of plastics under 3925, also at 18%. With all these at the same rate, the main risk is mis-describing the supply, not mis-rating it.

Measurement and minimum area billing

A common practice is to bill a minimum chargeable area per window even when the opening is smaller. GST is charged on whatever the contract price is, so the minimum-area amount is the taxable value. Spell out the rule in the quotation and print it on the invoice, so that the client cannot argue later that the excess is not consideration.

Façade contracts and e-way bills

Façade and structural glazing contractors move large consignments of glass and sections to high-rise sites. Each consignment above ₹50,000 needs an e-way bill, including movements from your fabrication unit to your own site under a delivery challan. Glass breakage in transit should be recorded, and any credit note for rejected panes must refer to the original invoice number.

Composition and the counter business

Many aluminium fabricators also sell sections and glass across the counter. If you opt for composition, the whole business under one PAN in that state must follow it; you cannot keep the shop under composition and the contracting business under normal tax. With turnover over ₹50 lakh, the service composition route closes, and most fabricators choose regular registration.

Common billing mistakes

Billing a full installed window package under HSN 7610 as goods while the work was actually done on site.
Not attaching a window schedule, so the engineer cannot match quantities to drawing marks.
Applying the minimum-area rule on the invoice without having it in the quotation, leading to deductions.
Issuing a credit note for broken glass without quoting the original invoice.
Quoting glass thickness only in the quotation and not on the invoice, so a client who later finds 4 mm instead of 5 mm panes has no document to compare against and withholds the final payment.

Aluminium windows and glazing contractor GST invoice: FAQ

What SAC code is used for glazing work?

Use 995471 for glazing services. Aluminium window installation with glass is usually billed under this code as a works contract at 18%.

What is the HSN for aluminium windows?

Aluminium doors, windows and their frames fall under HSN 7610, aluminium structures, at 18% GST.

What GST applies to toughened glass?

Toughened and laminated safety glass under HSN 7007 is taxed at 18%.

Are uPVC windows taxed differently from aluminium?

uPVC windows are builders' ware of plastics under 3925, also at 18%, so the rate is the same.

Can a commercial client claim credit on my glazing bill?

Credit is blocked under section 17(5) for works contracts and goods used in constructing immovable property, including façades and fixed partitions. A client selling the building as a works contract may be an exception.

Should the window schedule be part of the invoice?

Yes, attach it as an annexure or print it as line items. Each opening mark, size, area and glass type on the invoice lets the architect certify the bill quickly and becomes the reference for any later replacement or warranty claim.

Sources: CBIC — Notification 9/2025-Central Tax (Rate), 17 Sep 2025 · ICAI IDTC — Notification 9/2025-Integrated Tax (Rate) as corrected 18 Sep 2025 · CBIC — Scheme of Classification of Services (SAC annexure)

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