If you have a taxable income of INR 20 lakhs per annum, there are several ways you can save tax in India:

1. Maximize exemptions and deductions: You can claim exemptions and deductions under various sections of the Income Tax Act to reduce your taxable income. Some common exemptions and deductions include House Rent Allowance (HRA), investment in savings instruments like Public Provident Fund (PPF) and National Savings Certificate (NSC), and life insurance premium payments.
2. Invest in tax-saving instruments: You can invest in tax-saving instruments like Equity-Linked Saving Schemes (ELSS) and 5-year fixed deposits (FDs) to reduce your taxable income. These investments are eligible for tax benefits under Section 80C of the Income Tax Act.
3. Make use of the standard deduction: A standard deduction of INR 50,000 is allowed for salaried individuals. This deduction can be claimed in addition to exemptions and deductions under Section 80C.
4. Opt for the new tax regime: The government has introduced a new tax regime with lower tax rates, but without exemptions and deductions. You can opt for this regime if the lower tax rates result in a lower tax liability compared to the previous regime with exemptions and deductions.
5. Consider tax-saving salary structures: You can opt for a tax-saving salary structure that includes allowances like HRA and conveyance allowances, which are exempt from tax, in addition to reducing your taxable income.

It’s advisable to consult with a Tax professional to determine the best course of action for your specific situation and to ensure that you claim the maximum tax benefits that you’re entitled to.