https://help.tallysolutions.com/docs/te9rel64/Tax_India/gst/why_is_gst_not_calculated.htm

GST not Calculated Automatically

In few scenarios, GST will not be calculated automatically. You can do the following to automate the calculation.

Check the Tax Analysis : In the invoice press A : Tax Analysis for the breakup of tax values. The tax values will appear based on the intrastate or interstate transaction. As per the tax type shown in the Tax Analysis screen, select the relevant GST ledger in the invoice to automatically calculate GST.

Check if the nature of transaction is overridden in the invoice : If you have changed the Nature of transaction in the GST Details screen of the invoice, ensure the relevant GST ledgers are selected. For example, if you have changed the nature of transaction from intrastate to interstate, select integrated tax ledger and not central/state tax ledgers.

Check the HSN code and nature of transaction in the masters : Check if only the HSN code is defined in the sales or purchase ledger and tax rates with nature of transactions are defined in the stock item or stock group.

o If you want to capture the details defined in the ledger, ensure the HSN code and tax rates are defined in the ledger.

o If you do not want to use details of sales ledger, remove the HSN details and configure in stock item or stock group.

Check the tax rate and tax rate history in stock item : Check if the HSN code and tax rates are different for different applicable dates. If they are different, provide complete information with appropriate applicability date.

Check the GST Details defined in sales ledger and stock item : Check if the HSN code and tax rates defined in ledger match with the stock item. If it does not match, or the Tax Rate History shows different configurations applicable from different dates:

o Ensure the required details are defined either in ledger or stock item, or

o Provide the same details with the same applicability dates in ledger and stock item.

Check if tax ledgers are selected based on the place of supply : Depending on the place of supply, check if the:

o Central or state tax ledgers are selected for interstate party or natures of transaction.

o Integrated tax ledger is selected for intrastate party or natures of transaction.