Getting 234C interest tax to pay, why?

It is for the delay in deposit of advance tax.

Thank you both for your reply. I will remember from this year to pay advance tax in the same quarter in which I will get capital gain.

Interest under section 234C is imposed when there is a delay in payment of an instalment of advance tax. You pay interest under Section 234C if, Advance Tax is paid on or before 15th June is less than 12% of Assessed Tax