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What Is CST Duty?

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Last updated on 3 min read
CST duty is a 2% tax on inter-state sales in India when the buyer provides a valid C-Form; otherwise, the local state tax rate applies.

CST is a levy applied to goods sold across state lines in India. It kicks in when the buyer and seller operate in different states. As of 2026, the standard rate stays at 2%—but only if a C-Form gets filed. Miss that paperwork, and you’ll owe whatever the destination state charges instead.

Quick Fix: If you're a dealer moving goods between states, verify your C-Form submission to lock in the 2% CST rate before invoicing.

What's Happening

CST is an indirect tax on inter-state sales governed by the Central Sales Tax Act, 1956.

Central Sales Tax (CST) is an indirect tax governed by the Central Sales Tax Act, 1956. It targets inter-state sales—movements where goods cross state borders or are invoiced across state lines. CST is collected at the point of sale or movement, whichever happens first. The revenue ends up with the central government, but each state’s sales tax department handles the paperwork.

Step-by-Step Solution

Follow these five steps to apply CST correctly on inter-state sales in 2026.

Here’s exactly how to handle CST when you’re shipping goods from one Indian state to another this year.

  1. Confirm inter-state movement: Double-check that the buyer’s and seller’s states are different. Same-state sales? Skip CST—use your state’s VAT regime instead.
  2. Determine eligibility for the C-Form rate: Can the buyer issue Form C? If yes, slap that 2% CST rate on the invoice.
  3. Calculate CST amount: Multiply the taxable value by the correct rate (2% with Form C, or the state’s rate without it). Example: Taxable Value ₹100,000 × 2% = ₹2,000.
  4. Generate invoice: List CST as a separate line. Spell out the rate and reference the C-Form when you’ve got one.
  5. File return (Form A): Report inter-state sales in your CST return (Form A) every month or quarter, depending on how you’re registered.

If This Didn’t Work

Here’s what to do when CST isn’t applying the way you expected.
  • Missing Form C: If the buyer can’t cough up Form C, charge the local VAT rate instead of 2%. Keep proof that the buyer isn’t eligible for the lower rate.
  • Incorrect state code in invoice: Double-check the buyer’s GSTIN. The first two digits should match the destination state—no typos allowed.
  • Goods exempt from CST: Some items—like newspapers, books, and agricultural produce—are exempt when moved inter-state. Check the Central Sales Tax (Registration and Turnover) Rules, 1957 for the full list.

Prevention Tips

Follow these four habits to avoid CST headaches down the road.
  • Validate buyer GSTIN: Look up the GSTIN on the GST portal before you send the invoice. This confirms the buyer is legit and in the right state.
  • Maintain proper documentation: Hold onto signed C-Forms, delivery challans, and invoices for at least seven years. Digital copies are fine as long as you can pull them up fast.
  • Use e-Way Bills: Generate an e-Way Bill on the GST portal for every inter-state move over ₹50,000. It’s your proof of movement and keeps you compliant.
  • Quarterly reconciliation: Every three months, match your CST invoices against your GST returns. Make sure every inter-state sale is declared and taxed properly.
Alex Chen
Author

Alex Chen is a senior tech writer and former IT support specialist with over a decade of experience troubleshooting everything from blue screens to printer jams. He lives in Portland, OR, where he spends his free time building custom PCs and wondering why printer drivers still don't work in 2026.

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