Step 1) First Go to Master > Product Master > and open HSN/SAC wise GST rate.
Step 2) Add new HSN and add new GST % and enter the Applicable date which is appy new GST %.
Step 3) After that Press OK (F2) option.
Step 4) After that go to account maste and then select option name of “Update GST details”.
Step 5) Open update GST details after that select new GST HSN code.
Step 6) Now after that select a product which is updated to GST %.
Step 7) Press Ok