You can get returns of more than Rs 40 lakhs with a maturity of 15 years through the PPF scheme. How? If you invest a maximum of Rs 1.5 lakh every year for 15 years, the total deposit will be Rs 22,50,000.
Adding 7.1% annual interest to this, a return of Rs 18,18,209 is available. You can get Rs 40,68,209 till the maturity time. Depending on your personal financial situation, you can increase or decrease this investment amount.