For computing short term capital gain on sale of house the sale price wil be agreement value / Stamp value?

in case the stamp value is 25lacs whereas agreement value is 18 lacs the tax will be calculated on 18lacs / 25 lacs ?

It will be higher of both read section 50C of I T Act

Special provision for full value of consideration in certain cases.

50C. (1) Where the consideration received or accruing as a result of the transfer by an assessee of a capital asset, being land or building or both, is less than the value adopted or assessed by any authority of a State Government (hereafter in this section referred to as the 鈥渟tamp valuation authority鈥? for the purpose of payment of stamp duty in respect of such transfer, the value so adopted or assessed shall, for the purposes of section 48, be deemed to be the full value of the consideration received or accruing as a result of such transfer.

(2) Without prejudice to the provisions of sub-section (1), where鈥?br>
(a) the assessee claims before any Assessing Officer that the value adopted or assessed by the stamp valuation authority under sub-section (1) exceeds the fair market value of the property as on the date of transfer;

(b) the value so adopted or assessed by the stamp valuation authority under sub-section (1) has not been disputed in any appeal or revision or no reference has been made before any other authority, court or the High Court,

the Assessing Officer may refer the valuation of the capital asset to a Valuation Officer and where any such reference is made, the provisions of sub-sections (2), (3), (4), (5) and (6) of section 16A, clause (i) of sub-section (1) and sub-sections (6) and (7) of section 23A, sub-section (5) of section 24, section 34AA, section 35 and section 37 of the Wealth-tax Act, 1957 (27 of 1957), shall, with necessary modifications, apply in relation to such reference as they apply in relation to a reference made by the Assessing Officer under sub-section (1) of section 16A of that Act.

Explanation.鈥擣or the purposes of this section, 鈥淰aluation Officer鈥?shall have the same meaning as in clause (r) of section 2 of the Wealth-tax Act, 1957 (27 of 1957).

(3) Subject to the provisions contained in sub-section (2), where the value ascertained under sub-section (2) exceeds the value adopted or assessed by the stamp valuation authority referred to in sub-section (1), the value so adopted or assessed by such authority shall be taken as the full value of the consideration received or accruing as a result of the transfer.]

Definitely on the agreement value. If you're going to be paid only 18 lacs, why would you pay tax on 25?

By the way, everyone knows how much black money is involved in property business, including the department. So, consult your officer. He may not accept the agreement value!!!

sorry, there is some confusion in your question. how can the agreement value be less than the stamp value. anyway, the amount to be declared and tax paid for is the value what you show on the registration papers.