Ans:
The government deems a deductor as an assessee-in-default if they fail to deduct TDS or does not deposit it to the government's account in the following situations:
The deductor has not furnished the ITR under section 139, 139
The payer has not considered such expenditure or amount for computing income in the above-filed return.
The deductor has not paid the amount of tax due as per the return