GST invoice format for a diagnostic lab (pathology)
Pathology and diagnostic tests done to diagnose a disease are health care services, so a lab bills them without GST on a bill of supply using SAC 999316. What makes a lab bill different is the clinical detail: a sample or accession ID, the referring doctor, the test codes and the collection type. Labs also bill hospitals and corporates in bulk, and they buy reagents at 5% without being able to claim credit, so cost tracking matters more than in most trades.
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Sample prices are illustrative. Check the GST rate for your exact item or service before billing.
Extra fields a diagnostic lab invoice needs
Sample or accession ID
Each sample gets a unique ID that links the bill to the report. If a patient disputes a result or a charge, the ID lets you pull the collection time, technician and report from one reference.
Referring doctor
Most tests come on a doctor's prescription. Naming the referring doctor on the bill helps the patient's insurance claim and lets you analyse referrals, but avoid printing any referral fee or commission on the patient's bill.
Test name with internal code
Labs run hundreds of tests and profiles. Printing your internal code beside a plain-language name like 'HbA1c' or 'Lipid profile' prevents disputes over which test was ordered and charged.
Collection type (walk-in or home)
Home collection often carries an extra charge. Showing it as a separate line makes clear what the patient paid for and keeps the collection charge tied to the diagnostic service.
Report delivery date and time
Patients and hospitals want to know when results will be ready. The promised delivery time on the bill reduces calls to the front desk and records the turnaround you committed to.
Corporate or panel reference
For employer health check-ups or hospital outsourcing, a purchase order or panel reference on the bill lets the client's accounts team match it against their approval quickly.
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)
The definition of clinical establishment in the GST exemption notification covers any institution offering services or facilities that need diagnosis or treatment of illness, including investigative services. A pathology lab, collection centre or radiology centre testing patients for diagnosis therefore supplies exempt health care. The test fee, home collection charge and report are all part of that service. A lab that performs only exempt tests does not need GST registration under section 23, though many registered labs still exist because they sell some taxable services.
Testing that is not for health care is taxable
The exemption is for health care of patients. Tests done for other purposes, such as testing food, water or industrial samples, or lab services sold to a pharmaceutical company for clinical research, are not health care of a patient and are generally taxable services. A lab doing both must split its billing, issue tax invoices for the taxable work and track the two streams separately. Mixing them on one exempt bill is a common audit point.
Outsourced tests between labs
Many smaller labs send specialised tests to a reference lab. The reference lab's charge to the referring lab is still testing for diagnosis of a patient, so it is commonly treated as exempt health care. Keep the patient reference on the inter-lab bill so the link to patient care is clear. Commission or marketing fees paid to doctors or agents are not health care and do not share the exemption.
Reagents at 5% become a cost
Diagnostic kits and reagents under HSN 3822 dropped from 12% to 5% from 22 September 2025, and medical instruments under 9018 and 9027 also moved to 5%. Because a lab's output is exempt, it cannot claim input tax credit on these purchases, so the GST paid is part of your cost per test. The rate cut lowers that cost. Price your test menu using the tax-inclusive purchase price of reagents.
Bio-medical waste disposal is exempt
Services provided by a common bio-medical waste treatment facility to a clinical establishment for treating or disposing of bio-medical waste are exempt from GST. A lab should check that its waste contractor bills without GST under this entry rather than charging 18%. If a contractor charges tax wrongly, the lab cannot claim the credit, so the overcharge is lost.
Common billing mistakes
✕Printing doctor referral commissions on patient bills, which is both an ethics problem and not part of the exempt service.
✕Treating water or food testing for businesses as exempt health care, when it is a taxable testing service.
✕Paying GST on bio-medical waste disposal bills that should be exempt for a clinical establishment.
✕Issuing bills without a sample ID, which makes it hard to resolve disputes between the charge and the report.
Diagnostic lab GST invoice: FAQ
Is GST applicable on pathology tests?
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No, diagnostic tests done for a patient's diagnosis or treatment are exempt health care services. The lab issues a bill of supply without GST. Testing done for commercial purposes, such as food or water samples, is taxable.
Which SAC code applies to a diagnostic lab?
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SAC 999316 covers medical laboratory and diagnostic imaging services. Use it on all patient bills even though the rate is nil, so your reports and any GSTR-1 exempt summary are consistent.
Is home sample collection taxable?
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When it is part of collecting a sample for a patient's diagnostic test, home collection is part of the exempt health care service. Show it as its own line so the patient sees the charge clearly.
Can a lab claim GST credit on reagents and machines?
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Not for exempt patient testing. Input tax credit is blocked for exempt supplies, so GST on reagents and equipment is a cost. If the lab also has taxable income, it can claim credit in proportion to taxable turnover.