Professional tax is deducted on the total gross salary earned. If you are asking about tax deducted from the basic salary, please clarify so I can provide a more accurate response. To the best of my knowledge, there is no tax component calculated solely on the basic salary; the basic salary is primarily considered for PF (Provident Fund) calculations.
If you are referring to TDS (Tax Deducted at Source), then it is calculated based on the total taxable income.