what will happened if any flat owner is regular income tax payer but not aware / knowledge about the TDS and purchased a higher value flat from builder without any TDS deduction?

Ans: Hi
Ignorance of law does not bring any relief to the flat owner. The penal consequences would apply in this case and the following provisions are applicable:

Penal Interest is applicable from the date on which the deduction was to be made. The rate of penal interest would be 1.5% p.m if the TDS was deducted but not paid and 1% p.m. if the TDS was not deducted.

Late Fee of Rs. 200 per day would be applicable from the due date for filing the TDS return in Form 26QB however this would be maximum upto the amount of TDS i.e. if the total TDS is say Rs. 1 Lakh and the late fee works out to Rs. 2 Lakhs then the late fee would be limited to Rs. 1 Lakh.

The above two amounts have to be paid along with the TDS amount while filing the Form 26QB

In addition to the above, if the TDS return has not been filed within a year then the Tax Officer could levy a penalty which could range between Rs. 10,000 (minimum) and Rs. 1 Lakh (maximum)