What is HSN Code 9031? Full Details, GST Rate & Sub-Headings

If you have ever looked at an invoice for a measurement or test instrument and thought to yourself, “What the heck is the correct HSN code for this?”, you’re not alone. HSN Code 9031 is one of the most confusing HSN codes available, even for experienced professional accountants. 

What Even Is an HSN Code?

Harmonized System of Nomenclature (HSN) is a process that categorizes goods into internationally recognized codes. Fancy name, but the idea is simple. It’s an internationally accepted system that puts every product into a specific category. Under GST in India, every invoice for goods needs an HSN code. It’s not optional; it directly decides what tax rate applies to your supply.

Now here’s the thing. Most decent GST billing software will automatically retrieve HSN codes for you. But relying entirely on software without actually understanding the code? That’s a risk. Because when something gets flagged in your returns, you need to know why.

So What Is HSN Code 9031, Really?

HSN Code 9031 falls under Chapter 90 (Optical, Photo, and Precise Measuring Equipment and Checking Instruments). The official harmonized code description of HSN Code 9031 is: Measuring or Checking Appliances, Instruments, or Machines, not Explicitly Specified nor classified in Any Other Chapter; Profile Projectors. 

However, if you use better Invoicing software, the phrase “not specified or included elsewhere” is the key here. Basically, if you’re dealing in measuring or testing equipment and it doesn’t fit into a more specific Chapter 90 heading, it probably belongs under HSN Code 9031. It’s the chapter’s catch-all, but a very specific and important one.

Who Actually Uses This Code?

Honestly, more businesses than you’d think. HSN Code 9031 comes up regularly for:

• Manufacturers and traders of industrial measurement instruments
• Suppliers of profile projectors and optical comparators
• Companies dealing in non-destructive testing equipment
• Businesses selling dynamic balancing machines
• Dealers in coordinate measuring machines
• Anyone selling spare parts or accessories for the above will most likely be affected. 

People involved in precision engineering, quality control, or industrial inspection will find that this code applies as well. 

The Sub-Headings Under HSN Code 9031

The reason why this is, where the majority of people either go really deep or just throw in the towel and simply go by the four-digit code for everything, is due to not understanding the actual meaning of these sub-headings.

9031 10 – Balancing Machines

These machines test and correct imbalances in rotating components — such as rotors, crankshafts, turbine blades, and fan assemblies. Anything that spins and needs to be balanced before it goes into production or service.

9031 20 – Test Benches

Test benches simulate the real-world conditions for testing components. Load, vibration, pressure, and temperature. These are widely used in the automotive and aerospace industries to uncover problems that might become field failures. 

9031 41 – Profile Projectors

Also called optical comparators. They magnify a component’s silhouette and project it onto a screen so it can be measured against a reference template. Standard stuff in precision tool rooms and quality labs.

9031 49 – Other Optical Instruments

Anything optical that measures or inspects and doesn’t specifically fit under 9031 41 lands here. If it uses light or lenses to check something, this is likely the right bucket.

9031 80- Other Instruments and Machines

The widest sub-heading of the lot. Coordinate measuring machines, roundness testers, surface roughness instruments, if it measures or checks something and hasn’t been captured by a more specific sub-heading, it comes here.

9031 90 – Parts and Accessories

Selling a spare probe? A replacement sensor? A calibration fixture for a CMM? That’s 9031 90 — not 9031 80. Parts and accessories always have their own subheading, and mixing them up is a very common mistake.

What’s the GST Rate on HSN Code 9031?

Simple answer — 18%.

That’s 9% CGST plus 9% SGST for supplies within a state, or 18% IGST for inter-state movement. And this rate applies across all sub-headings — 9031 10 all the way through 9031 90.

One thing worth remembering, though — GST Council notifications can revise rates. So before you raise a big-ticket invoice, just confirm on the GST portal. If you’re using invoicing software, make sure it’s pulling live or regularly updated rate data and not working off something hardcoded from two years ago.

How to Get the HSN Right on Your Invoice

Two things to keep in mind based on your turnover:

Up to ₹5 crore — 4-digit HSN is fine. So just “9031” works. Above ₹5 crore — you need 6 or 8 digits. That means specifying the sub-heading — 903110, 903180, 903190, and so on.

Your product description on the invoice also needs to match. Writing “9031 80” but describing the item as “optical comparator” is going to raise eyebrows. Consistency matters.

Good invoicing software takes care of most of this — it helps you pick the right sub-heading, fills in the GST rate, and keeps your invoice format compliant. If your current invoicing software isn’t doing that, it might genuinely be worth switching.

Mistakes That Keep Coming Up

Wrong heading within Chapter 90 — Flow measurement instruments are under 9026. Physical or chemical analysis equipment sits in 9027. Oscilloscopes and electronic measuring instruments belong in 9030. HSN Code 9031 is specifically for what’s left over. If something fits a named heading, use that heading — not 9031.

Using 9031 as a catch-all for everything — It is a catch-all within Chapter 90, yes. But that doesn’t mean you can classify anything vaguely measurement-related under it. It has a defined scope, and going beyond that scope is a compliance issue.

Lumping parts under the main product heading — Parts always go under 9031 90. Always. Don’t mix them in with the finished instruments.

Skipping the HSN on B2B invoices — Your buyer’s ITC depends on the HSN you declare. A wrong or missing code on your invoice can lead to their credit being questioned — and that dispute will land right back on your desk.

Why It’s Worth Getting Right

A wrong HSN code creates a chain reaction that’s genuinely annoying to deal with. Your GSTR-1 won’t match your buyer’s GSTR-2B. Their ITC gets flagged. Questions come your way. Everyone spends time fixing something that should never have been a problem.

An effective GST billing software package should not remove the necessity of comprehending the classifications of your invoices; however, it should ensure that the accurate codes, rates, and formats will appear on any given invoice at all times. This is a good ROI on your purchased software. 

Conclusion 

Chapter 9031 of the HSN can be defined as Precision Measuring/Checking Instruments – anything within Chapter 90 which does not have a specific subheading. Examples include balance machines, test benches, CMM accessories, etc. All goods listed for this chapter fall under an 18% GST rate; therefore, you should ensure that you have a complete knowledge of each subheading and take advantage of GST billing and invoice Software such as MargBooks software to ensure that accurate classifications are maintained and that invoices are free from errors. These two things will be instrumental in ensuring that there will be easy-to-complete returns versus a mountain of reconciliation work.

If the description of an item is not clear regarding insertion of a new product, unusual measuring instrument, or in respect to an export shipment, take a moment to verify that item’s HSN Classification through the CBIC Portal or with a GST Consultant. A simple verification is much quicker than receiving a lengthy notice.

Disclaimer: As GST Rates and HSN Classifications may fluctuate based on decisions by the GST Council, please ensure that you verify the current rates on the Official GST Portal or with a qualified tax professional prior to issuing any invoice based on those classifications.