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Rate Migration & Pricing Impact Calculator

Old vs New GST Rate Comparison Tool

Instantly analyze price variance, tax incidence shifts, and consumer savings resulting from GST rate revisions and slab rationalizations.

Common Rate Migration Presets Click to auto-populate rates

Base price before any GST is added.

Determines CGST/SGST local tax split versus integrated IGST.

Old Tax Scenario

12% GST
Net Base Taxable Value ₹1,000.00
Central GST (CGST @ 6%) ₹60.00
State/UT GST (SGST @ 6%) ₹60.00
Total Old Tax Amount ₹120.00
Total Customer Price (MRP) ₹1,120.00

New Tax Scenario (Revised)

5% GST
Net Base Taxable Value ₹1,000.00
Central GST (CGST @ 2.5%) ₹25.00
State/UT GST (SGST @ 2.5%) ₹25.00
Total New Tax Amount ₹50.00
Total Customer Price (MRP) ₹1,050.00
Price Variance & Tax Incidence
₹0.00

Calculating rate differential...

Statutory Guidance

How the Old vs New GST Rate Comparison Works

Under the Indian Goods and Services Tax (GST) framework governed by the Central Goods and Services Tax (CGST) Act, 2017 and respective State GST acts, tax rates on commodities and services undergo periodic rationalization through GST Council recommendations and CBIC notifications. When a rate revision takes effect, manufacturers, distributors, retailers, and service providers must immediately recalibrate their pricing structures, Point of Sale (POS) systems, and ERP billing masters.

Our Old vs New GST Rate Comparison Tool provides an automated mathematical breakdown of price shifts, tax variations, and consumer savings across legacy and rationalized GST slabs.

1. Mathematical Formulas for Tax and Price Variance

Depending on whether your business operates on backward tax-inclusive MRP pricing or forward base pricing, two core formulas determine the outcome:

  • Forward Base Pricing (Standard B2B):
    Old Tax = Base Price × (Old Rate ÷ 100)
    New Tax = Base Price × (New Rate ÷ 100)
    Net Tax Variance (ΔTax) = New Tax − Old Tax
    Revised Retail Price = Base Price + New Tax
  • Backward MRP Extraction (Packaged Goods / Retail):
    Extracted Base Price = Original MRP ÷ (1 + Old Rate ÷ 100)
    Revised Mandatory MRP = Extracted Base Price × (1 + New Rate ÷ 100)

2. Section 171 Anti-Profiteering Mandate

A critical legal dimension of any downward GST rate revision is compliance with Section 171 of the CGST Act. The law strictly mandates that:

"Any reduction in rate of tax on any supply of goods or services or the benefit of input tax credit shall be passed on to the recipient by way of commensurate reduction in prices."

If a product previously taxed at 12% is reclassified to 5%, the seller cannot pocket the 7% tax differential by keeping the customer-facing MRP unchanged while pocketing extra profit. Anti-profiteering complaints are investigated under the jurisdiction of the Competition Commission of India (CCI), and non-compliant suppliers can be ordered to refund excess amounts with 18% statutory interest, pay heavy penalties, or face business deregistration.

3. Transitory Invoicing Rules under Section 14 (Time of Supply)

When tax rates change mid-month, determining whether an invoice should reflect the old or new rate depends on Section 14 of the CGST Act. The applicable rate is determined by the intersection of three pivotal operational events:

  1. Date of Supply of Goods or Services
  2. Date of Issue of Invoice
  3. Date of Receipt of Payment (Bank credit or book entry)

As a general legal standard, whichever two of these three events occur after the rate change date will dictate the applicable rate. For example, if goods were dispatched prior to the rate change, but both the invoice was issued and payment was credited into the bank account after the rate change, the new rate applies.

4. Impact of Rate Revisions on Input Tax Credit (ITC)

Rate changes also have direct consequences for input tax recovery:

  • Movement between taxable slabs (e.g. 18% to 5%): Does not require any retrospective reversal of ITC claimed on raw materials or capital goods purchased at earlier higher rates.
  • Movement to Exempt (0%): Triggers mandatory reversal of ITC on inputs and stock on hand under Section 18(4) and Rule 42 of the CGST Rules.
  • Inverted Duty Structure: Where the output rate drops below the tax rate on raw materials (e.g., input fabric at 12% and output garments at 5%), manufacturers become entitled to file for an Inverted Duty Structure refund under Section 54(3)(ii).

5. Retail Relabeling & Legal Metrology Rules

Under the Legal Metrology (Packaged Commodities) Rules, retailers are legally prohibited from selling packaged commodities at a price higher than the printed MRP. Following GST rate reductions, the Department of Consumer Affairs traditionally permits manufacturers, packers, and importers to declare revised lower MRPs on unsold pre-packaged stock via stamped, stickered, or online printed tags, provided the original MRP remains visible.

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Frequently Asked Questions

Comprehensive answers regarding GST rate revisions, pricing formulas, and anti-profiteering compliance.

What is the difference between legacy GST slabs and rationalized GST rates?
Under the legacy GST framework, goods and services were classified into five primary slabs: 0% (exempt), 5%, 12%, 18%, and 28% (plus applicable compensation cess). Ongoing rate rationalization simplifies this multi-tier structure by phasing out the 12% slab—moving essential goods to 5% and standard goods to 18%—while introducing consolidated luxury brackets (such as 40%) to eliminate separate cess calculations.
How do I calculate the price and tax impact of a GST rate change on a product?
To calculate the exact price impact: (1) Determine the base price excluding tax. If you only have an MRP, reverse-calculate the base price using: Base Price = Old MRP ÷ (1 + Old Rate / 100). (2) Calculate old tax = Base Price × Old Rate / 100. (3) Calculate new tax = Base Price × New Rate / 100. (4) The price impact equals New Tax minus Old Tax. If negative, the consumer saves money; if positive, retail prices increase.
Is a business legally required to reduce prices if the GST rate drops on its products?
Yes. Under Section 171 of the CGST Act (Anti-Profiteering), any reduction in the rate of tax on any supply of goods or services, or the benefit of input tax credit, must be passed on to the recipient by way of a commensurate reduction in prices. Failure to pass on tax reductions can trigger investigations by the Competition Commission of India (CCI), mandatory refunds to consumers, and statutory penalties.
Does a reduction in GST rate require a business to reverse Input Tax Credit (ITC)?
A reduction between taxable brackets (e.g. from 18% down to 12% or 5%) does NOT require any reversal of ITC already availed on previously purchased inputs or capital goods. However, if a product is reclassified from taxable to wholly exempt (0%), the taxpayer must reverse proportionate ITC on raw materials and semi-finished/finished goods held in stock under Section 18(4) and Rule 42 of the CGST Rules.
Which GST rate applies to invoices issued during a rate transition period (Section 14)?
Under Section 14 of the CGST Act (Determination of rate of tax in change of rate), applicability depends on three dates: supply of goods/services, issue of invoice, and receipt of payment. If the supply occurs before the rate change but both the invoice and payment occur after the change, the new rate applies. If the supply and invoice occur before the change, the old rate applies regardless of payment date.
How does a GST rate change affect Inverted Duty Structure (IDS) refund claims?
An Inverted Duty Structure occurs when the GST rate on inward inputs is higher than the rate on outward supplies. If an outward rate is reduced (e.g., from 18% to 5%), it may create an inverted duty structure, entitling the manufacturer to claim a refund of accumulated unutilized ITC under Section 54(3)(ii) of the CGST Act (subject to statutory exclusions for input services).
What is the 40% GST slab and which commodities does it cover?
The 40% GST slab is a unified demerit and luxury tax bracket designed to replace the complex mechanism of a 28% base GST rate plus variable Compensation Cess. It covers sin goods, high-end motor vehicles, aerated sugary beverages, tobacco products, and pan masala, ensuring revenue neutrality while streamlining the invoicing and reporting process.
How does a GST rate change impact B2B buyers compared to B2C retail consumers?
For registered B2B buyers who claim full Input Tax Credit, a GST rate change is generally cashflow-neutral because any tax paid on purchases is set off against output tax liabilities. For unregistered end consumers (B2C), any change in GST directly impacts total out-of-pocket expenditure, altering market demand and product affordability.
Can a seller issue Credit Notes or Debit Notes for rate adjustments after delivery?
Yes. Under Section 34 of the CGST Act, if an invoice was raised at an old rate and the statutory effective date mandates a revised rate, the supplier can issue a Debit Note (if the rate was increased) to recover the tax differential, or a Credit Note (if the rate was reduced) to pass on the tax saving to the recipient.
Do retailers need to print new MRP stickers on existing inventory after a rate change?
Under the Legal Metrology (Packaged Commodities) Rules and ministry advisories issued during GST rate revisions, manufacturers, packers, and retailers are permitted to affix revised price stickers on existing unsold inventory showing the lower revised MRP alongside the original MRP, ensuring consumers are not overcharged.