The government approved valuer should mention the reasons or basis on which the valuer has taken such higher value if he has some proper reason then it may accepted otherwise not.
The income tax department also need some basis on which such amount has been calculated by valuer. If the basis are not strong your value will surely be rejected. You can check at what value the land were sold near by may be you find some high value transaction to support.
Or he needs to state something that near your land there is a road or something because of which value of your land needs to be higher than others.
If he finds any mistake then he will reject your valuation and at that time you need to ask AO to go to government approved valuer because he will take the least amount.
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