purchases come under the category of expenses and it's covered by section 40A(3) and the threshold is 20000 till a.y. 2017-18 and rs. 10000 from a.y. 2018-19. in respect of sales if u receive cash more than 2 lakhs from a person in a day or in respect of single transaction or event, then 100% of amount shall be levied as penalty u/s. 269st