Introduction
You can file your own GST returns. The GST portal exists precisely so taxpayers don't need a CA for routine filings. Thousands of small sellers do it every month.
But "can you" and "should you" are different questions — and the answer changed after September 22, 2025, when GST 2.0 restructured the slabs and added a layer of rate verification that didn't exist before.
What GST Return Filing Actually Involves
Filing GST returns is not one task. It's three recurring tasks every month, each with its own data source, due date, and error type:
GSTR-1 (due 11th of every month) — You report every outward sales invoice from the previous month: buyer GSTIN, invoice number, taxable value, and the GST rate applied. For marketplace sellers, this means reconciling your Amazon, Flipkart, and Meesho settlement reports against your actual invoices. One mismatched GSTIN on a B2B invoice and your buyer's ITC claim gets blocked.
GSTR-3B (due 20th of every month) — The summary return where you declare total sales, total ITC, and pay the net GST liability. Underpaying here triggers interest at 18% per annum from the due date. Overpaying is your money sitting with the government until your next filing.
GSTR-2B reconciliation (done before filing GSTR-3B) — The portal auto-generates your GSTR-2B showing which ITC you can legally claim, based on your suppliers' GSTR-1 filings. If you claim ITC that your supplier hasn't reported, the department can demand it back with interest. This reconciliation step is where most DIY filers lose money.
None of this is technically complex. But all of it requires attention to detail on a fixed monthly schedule — with real financial consequences for errors.
Where GST 2.0 Made DIY Filing Harder
Before September 22, 2025, you filed at the rate your product had been classified at for years. The rate was stable; the process was mechanical.
GST 2.0 abolished the 12% slab and moved over 200 product categories either to 5% or 18%. If any of your products changed rate, every invoice you've raised since September 22 must reflect the new rate. Not the old one. Not a blended average. The correct rate from the correct date.
A seller who missed this and kept filing at 12% for October, November, and December 2025 has three months of GSTR-1 mismatches sitting on the portal — mismatches that show up in their buyers' GSTR-2B and will eventually generate automated reconciliation notices.
The fix is an amendment in GSTR-1, not a fresh filing. It's doable, but it's not obvious if you haven't handled an amendment before.
Check which rate applies to your products after GST 2.0 →
The TCS Detail Most Sellers Get Wrong
Every marketplace — Amazon, Flipkart, Meesho — deducts TCS (Tax Collected at Source) at 1% of the net taxable value on your payouts. This is not a GST rate. It's a tax deduction at source that appears in your GSTR-2B as credit to claim.
Many DIY filers either:
- Don't claim the TCS credit (leaving money on the table every month), or
- Claim it in the wrong field, which creates a mismatch
Your total monthly TCS credit from all platforms shows up in your GSTR-2B under "TCS credit available." It needs to be claimed in Table 8 of GSTR-3B. At ₹5L/month GMV, that's ₹5,000/month in TCS — ₹60,000/year — that should be offsetting your GST liability or coming back as a refund.
When DIY Makes Sense
You can realistically file your own returns if all of these are true:
- You sell on one platform only (one settlement report to reconcile)
- Your monthly turnover is under ₹15 lakh (manageable invoice volume)
- All your products fall in a single GST slab (no rate classification ambiguity)
- Your suppliers file their GSTR-1 on time (your GSTR-2B matches your invoices)
- You have 3–4 hours available around the 10th and 19th of every month
Kiran sells handmade cotton bags on Meesho. His products are at 5% GST, his suppliers are his own family workshop, and he does about 200 orders a month. He files his own GSTR-1 and GSTR-3B in about two hours monthly. For him, DIY is the right call — it costs nothing and he understands exactly what he's filing.
When to Stop DIY-ing
Hand off your GST filing when any of these appear:
- Multiple platforms — Amazon + Flipkart + your own D2C store means three reconciliation streams with different TCS rates, settlement periods, and invoice formats. Errors multiply with each platform added.
- Products in multiple slabs — If you sell both garments (5% or 18% post- GST 2.0 depending on price point) and accessories (18%), each GSTR-1 entry needs the right rate for the right item. One wrong rate on one line item cascades into ITC issues for your buyers.
- Monthly turnover above ₹25 lakh — At this volume, the cost of a CA filing error or a missed ITC claim typically exceeds the annual fee for professional filing. The maths inverts.
- GST notices received — A notice means the department has identified a discrepancy. Responding incorrectly can escalate it. This is not the moment to continue self-filing.
- ITC refund pending — Inverted duty refund applications under Rule 89 are not something to file yourself the first time. One wrong field blocks the refund for 90+ days.
The Step-by-Step if You're Filing Yourself
If you're in the "DIY makes sense" category, here's the actual process for GSTR-1 and GSTR-3B for FY 2025-26:
GSTR-1 (file by the 11th):
- Download your previous month's settlement report from each marketplace
- Separate B2B invoices (buyers with a GSTIN) from B2C (individual buyers)
- Verify the GST rate on each product — cross-check against your HSN code and the GST 2.0 rate table if any products changed slabs after Sept 22
- Log in to the GST portal → Returns → GSTR-1 → select the tax period
- Upload B2B invoices in Table 4A (GSTIN, invoice number, value, tax rate)
- Enter B2C summary in Table 7 (aggregate by state and tax rate)
- Preview, submit, and file with DSC or EVC
GSTR-3B (file by the 20th):
- Open your GSTR-2B on the portal — note the ITC available and TCS credit
- Reconcile GSTR-2B ITC against your purchase register — only claim what matches; don't claim ITC your supplier hasn't reported
- Log in → Returns → GSTR-3B → select tax period
- Enter outward supply summary (total taxable value, tax by rate slab)
- Enter eligible ITC in Table 4 (IGST, CGST, SGST separately)
- Enter TCS credit in Table 8
- Compute net tax liability = Output tax − ITC − TCS credit
- Pay the balance via challan before submitting
- File with DSC or EVC
The one thing most DIY guides skip: After filing GSTR-3B, download the filed return PDF and save it. You'll need it for loan applications, CA verifications, and any future GST notices referencing the period.
The Real Comparison
A CA-assisted filing service for GSTR-1 and GSTR-3B typically costs ₹999–₹2,500/month depending on transaction volume. At ₹1,500/month, that's ₹18,000/year.
One missed ITC refund of ₹5,000/month over 12 months = ₹60,000 left unclaimed. One rate error leading to a GST demand notice = ₹X,000 in penalties plus CA fees to respond. One incorrect TCS claim that triggers a mismatch = time and stress that doesn't show up on a balance sheet but absolutely shows up in your month.
The question isn't whether you can file yourself. It's whether the time and error risk are worth the money saved — and that answer is different at ₹3L/month GMV vs ₹30L/month GMV.
See what Dhanaay's CA partner filing service includes and costs →