Which amount shall be taken to calculate interest under Section 234D?
Where the amount is refunded on summary assessment, but no refund is found due on regular assessment, the interest shall be charged on the whole amount of the tax refund.

Further, if any refund is granted to the assessee after summary assessment and the refund so granted exceeds the amount refundable on regular assessment, the interest shall be charged on the such excess amount refunded to the assessee.​