Interest on calls in arrears - treatment as per income tax

Dear Experts

A company makes a rights issue and keeps it open for a period of 90 days with a condition that shareholders subscribing beyond 30 days and with in 90 days shall pay interest @ 12% p.a. from the date of opening of subscripttion. How to treat such interest in the books of account. Can we credit the interest to Share premium account ? Is it chargeable as interest income under the income tax act ?

Thanks in advance