computing income

An expense could be disallowed for the following reasons:

• Any tax amount deductible on certain expenses like TDS wasn’t deducted while making the payment.
• The expenditure is not associated with the conduct of such business or profession.

Taxpayers making cash payments for their goods or services are allowed as expenditures under this provision if the sum of such payment is less than Rs. 10,000. 

https://www.indiafilings.com/learn/expenses-disallowed-under-income-tax/