There is total 22 sector where you can invest for tax rebate.
Suppose you earned Tk 10 lakh from July 2022 to June 2023. According to the tax policy you do not have to pay tax for the first three lakh of your taxable income. So, you have Tk 7 lakh that you will have to pay tax for. Now for the first Tk1 lakh you have to pay at a rate of 5%, which comes to Tk 5,000. For the next three lakh you pay at the rate of 10%, which comes to 30,000.
Finally, you Tk 45,000, at the rate of 15%, for the last three lakhs. So, your total tax payable is Tk 80,000.
Now, suppose you decide to invest Tk 2 lakh in Bangladesh capital market, since 20% of your total income can be invested in savings. Therefore, you will get 15% concession on the Tk 2 lakh invested, or Tk 30,000. Since your taxable income is Tk 1,000,000 you only have to pay Tk 50,000.