Aerator Gear Boxes and Spares Attract 18% GST Rules AAR
Tamil Nadu AAR ruled that gear boxes and spare parts for prawn farming aerators attract 18% GST, not 5%.
- Ruling
- Advance Ruling No.53/ARA/2026, dated 18.08.2026
- Dated
- 18 Aug 2026
- Authority
- Authority for Advance Ruling
This page was written by Patron Accounting’s AI from the official release and reviewed before publishing. It explains the document in plain language. It is not the document itself. Where this page and the original differ, the original governs.
The short version
- BAS-J Industries asked if aerator gear boxes qualify for 5% GST rate
- Authority ruled aerator gear boxes attract 18% GST under HSN 84834000
- Spare parts like gears and shafts attract 18% GST under HSN 84839000
- Specific mechanical component entries override general agricultural machinery headings
In short
BAS-J Industries manufactures gear boxes and spare parts used in prawn farming aerators. The company asked whether its products could be classified under HSN 8436 as agricultural machinery to claim a lower GST rate of 5%. They argued that because the parts are used exclusively for aquaculture aerators, they should be taxed at the same rate as the main machine.
What has changed
How it worked before
The company was paying 18% GST under HSN 8483 but wanted to lower the tax burden to 5%. Businesses often assume that specialized parts custom-built for agricultural equipment can automatically take the concessional tax rate of the main machine.
What has changed
The Authority for Advance Ruling (AAR) in Tamil Nadu held that aerator gear boxes do not qualify as complete agricultural machinery. Gear boxes are specifically listed under HSN 84834000 and attract 18% GST under Notification No. 9/2025-Central Tax (Rate). Spare parts supplied separately, such as pinions, shafts, and gear wheels, fall under HSN 84839000 and are also taxed at 18% GST. In practice, specific machine component headings take priority over general end-use machine classifications.
Who this affects
Manufacturers and suppliers of gear boxes, shafts, pinions, and mechanical transmission parts custom-built for agricultural or aquaculture equipment.
An example
Apex Transmissions manufactures custom gear shafts designed strictly for tractor harvesters. The owner wants to know if they can bill these shafts at 5% GST under agricultural machinery instead of 18% GST as general transmission parts. Based on this ruling, GST law requires mechanical parts to be classified under their specific component code (HSN 8483). Apex must continue billing the shafts at 18% GST despite their agricultural use.
What you should do
Check your product catalog to ensure general mechanical transmission parts are classified under component headings like HSN 8483 rather than end-use machinery headings. Note that Advance Ruling No.53/ARA/2026 binds only BAS-J Industries and its local tax officer. If you supply similar parts, consult a tax professional or file your own advance ruling before changing your tax rates.
If you do nothing
If you reduce your GST rate from 18% to 5% by misclassifying parts under agricultural equipment, tax authorities can issue recovery notices. You will have to pay the unpaid 13% tax difference along with interest and mandatory penalties. This can lead to heavy financial losses and disputes during GST audits.
The terms explained
- HSN Code
- A international numerical coding system used under GST to classify products and fix their applicable tax rates.
- Advance Ruling
- A written tax decision given by tax authorities to a business regarding how GST rules apply to its specific operations.
- CGST Act
- The Central Goods and Services Tax Act, which governs the central portion of GST collected on sales within a state.
The ruling in detail
Authority for Advance Ruling
M/s BAS-J Industries
Advance Ruling No.53/ARA/2026, dated 18.08.2026 · Tamil Nadu
Questions before the authority
- The product classifiable under HSN 84368090 ("Other Agricultural Machinery") as per the First Schedule to the Customs Tariff Act, 1975 (made applicable to GST classification under Section 9 of the CGST Act read with Section 5 of the IGST Act), is covered under Entry No. 434 of Schedule-I of Notification No. 9/2025-Central Tax (Rate) dated 17.09.2025, and accordingly attracts GST at the rate of 5% (2.5% CGST + 2.5% SGST).
- That the Spare parts, components, and accessories used in, or supplied for growing of prawns which are essential for, or form part of, the prawn farming aerator machinery falling under HSN 84368090 ("Other Agricultural Machinery") - are also eligible to be taxed at the same rate of 5% (2.5% CGST + 2.5% SGST) in terms of the principle that parts of goods are classified and taxed in accordance with the classification of the main equipment, unless specifically excluded, thereby falling under Entry No. 434 of Schedule-I of Notification No. 9/2025-Central Tax(Rate) dated 17.09.2025.
Facts
The applicant is a manufacturer and supplier of aerator gear boxes and their spare parts (such as bevel pinions, bevel gears, helical gears, worm shafts, and worm wheels) used exclusively in aquaculture aerators for prawn farming. They sought clarity on whether their gear boxes and individually supplied spares could be classified under HSN 84368090 as agricultural machinery to claim the concessional GST rate of 5% under Entry No. 434 of Schedule-I of Notification No. 9/2025-Central Tax (Rate). Currently, the applicant had been adopting HSN 8483 attracting 18% GST.
Ruling
| Question | What the authority ruled |
|---|---|
| Classification and GST rate for aerator gear boxes | Attracts 18% GST under HSN 84834000 Does not merit classification under HSN 8436 for 5% GST rate |
| Classification and GST rate for spare parts of gear boxes supplied separately | Attracts 18% GST under HSN 84839000 Does not merit classification under HSN 8436 for 5% GST rate |
The Authority held that aerator gear boxes do not qualify for classification under HSN 8436 and are subject to **18% GST under HSN 84834000**. Furthermore, spare parts of gear boxes supplied separately are classifiable under **HSN 84839000 attracting 18% GST**.
Reasoning
In accordance with the General Interpretative Rules, when a specific entry describes the goods, it overrides a general entry. Gear boxes are specifically covered under subheading 84834000 ("Gears and gearing... gear boxes and other speed changers") and attract 18% GST under Sl. No. 468 of Schedule-II. The applicant supplies mechanical transmission devices rather than complete agricultural or aquaculture aerator machinery falling under HSN 8436. When transmission elements like pinions, shafts, and gear wheels are supplied separately as spare parts, they are correctly classifiable under HSN 84839000 as parts of heading 8483, also attracting 18% GST.
Provisions relied on
- Section 9 of CGST Act, 2017
- Section 5 of IGST Act, 2017
- Section 97 of CGST Act, 2017
- Notification No. 9/2025-Central Tax (Rate) dated 17.09.2025 (Schedule-I Sl. No. 434, Schedule-II Sl. No. 468)
- HSN 8436
- HSN 84834000
- HSN 84839000
For the practitioner
This ruling establishes that general mechanical transmission components such as gear boxes and individual gears cannot be reclassified under end-use agricultural equipment headings (HSN 8436) merely because they are custom-designed for aquaculture machinery. Tax practitioners should advise clients supplying parts or sub-assemblies that specific tariff headings (e.g., HSN 8483) take precedence over general machinery headings, preserving the 18% tax rate.
Source
This is a summary prepared from the published order, which is a scanned document. It is a reading aid and not the authority: where the two differ, the order governs. Verify every provision against the original before relying on it.
Original order: https://www.gstcouncil.gov.in/sites/default/files/AAR/bas-j_industries_aar_order.pdf
Legibility of the scan, as read: high.
Prepared 16-10-2026.
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