How much returns can I expect after 21 years?

I am investing Rs 2,500 per month via SIP in SBI Magnum Global Fund – Regular Plan (Growth) since the last one year. I am planning to invest for the next 20 years. What can I expect from this SIP after 21 years, and how much tax will I have to pay on this after 21 years?
--Pankaj Garg

Abhay Shah, certified financial planner, responds:

It is not possible to answer you query as we can’t be certain how much returns the scheme would offer you in future. However, what is certain is that you will definitely create wealth through this. And it will be far better than traditional financial instruments like FDs, RD, POST, PPF or NPS, etc.

You can expect to get a CAGR of 10-12 per cent in next 20 years. As per the current Income Tax provisions, there will be no tax on the returns after 21 years. Investments held in equity mutual funds qualify for long-term capital gains tax which is nil at the moment.