Income tax related query

Discount on Zero Coupon Bond is allowable to Delta Ltd. on pro-rata basis.
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Total Amount of Discount = 1,15,000 X Rs. (110 – 90) = Rs. 23,00,000
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Date of issue: 10.09.2013
- As it is less than 15 days, it shall be ignored and date of issue will be taken as 01.09.2013.
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Date of redemption: 22.09.2025
- As it is 15 days or more, it shall be increased to one month and so redemption date will be taken as 30.09.2025.
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Total life of the bond: 01.09.2013 to 30.09.2025 = 145 months.
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Prorated discount for one month = 23,00,000/145 = Rs. 15,862
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Amount of discount allowable for the P.Y. 2013-14
= Rs. (15,862 X 7) = Rs. 1,11,034 [01.09.2013 to 31.03.2014 = 7 months]
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Amount of discount allowable for the P.Y. 2014-15 to 2024-25
= Rs. (15,862 X 12) = Rs. 1,90,344 per year for 11 years
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Amount of discount allowable for the P.Y. 2025-26
= Rs. (15,862 X 6) = Rs. 95,172 [01.04.2025 to 30.09.2025 = 6 months]

As per Rule 8C of the Income-tax Rules, 1962, for the purposes of section 36(1)(iiia), the pro rata amount of discount on a zero coupon bond shall be computed in the following manner:
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(a) the period of life of the bond shall be converted into number of calendar months and, for this purpose, where the calendar month in which the bond is issued or the bond matures or is redeemed contains a part of a calendar month then, if such part is fifteen days or more than fifteen days, it shall be increased to one calendar month and if such part is less than fifteen days it shall be ignored.
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(b) the amount of discount shall be divided by the number of calendar months determined in accordance with clause (a)
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(c) where one or more than one calendar month out of calendar months determined in accordance with clause (a) is or are included in a previous year, the amount determined in accordance with clause (b) shall be multiplied by the number of calendar months so included and the amount so arrived at shall be taken to be the pro rata amount of discount for that previous year.