Query as understood, 
“A registered dealer under the regular GST scheme is engaged only in trading of exempted goods. For the financial year 2024–25, the dealer filed nil GSTR-3B returns but declared sales of ₹30 lakhs (exempted goods) in the Income Tax Return (ITR). Is it compulsory to adjust the turnover difference between ITR and GST returns? What is the correct procedure for this?”
Answer:
Under GST law, even if your goods are exempt and no GST is payable, you are still required to report the value of exempt sales in your GST returns. This helps the authorities understand the total turnover of your business and reconcile it with the figures declared in your income tax return.
In GSTR-3B, details of such exempted sales must be shown in Table 3.1(c) under the heading “Other outward supplies (nil rated, exempted)”.
This ensures that the total turnover reported in GST matches the business turnover shown in your books and income tax return.
If you have already filed nil GSTR-3B returns for the entire year, you can disclose the total value of exempt sales in the Annual Return (GSTR-9) under the part meant for exempt and nil-rated supplies.
This disclosure is important for transparency and to avoid any notice or query due to a mismatch between ITR and GST data.

Is turnover adjustment compulsory?
No, there is no legal requirement to “adjust” the turnover difference between ITR and GST returns because exempt sales are outside the tax net.
However, reconciliation is compulsory in practice. You should maintain proper records and be able to explain the reason for the difference — namely, that your goods are exempt from GST.

What you should do:

1. Report exempt sales properly in GSTR-3B under the exempted column (Table 3.1(c)) in future returns or in GSTR-9 for the current year.
2. Maintain a reconciliation statement showing that the ₹30 lakh turnover declared in ITR represents exempt goods, which do not attract GST.
3. Keep supporting documents such as invoices, purchase and sales registers, and the relevant GST exemption notification.
4. Provide an explanation if any department queries the difference — that your GST returns show nil taxable supplies because all your goods are exempt.

Summary:

• The difference between ITR turnover and GST returns does not require any adjustment entry.
• You must disclose the exempt turnover in GSTR-3B and/or GSTR-9 for proper reporting.
• Keeping a clear reconciliation and documentation will help you easily explain the difference in case of any verification or scrutiny.