TDS Calculations

Dear all 
I need an advice relating to the tds
Suppose I had given contract of 150000 to xyz company in Dec 2020 and the part contract has been completed by company and I had paid the part amount of 75000 on 1st Feb 2021 but fail to deduct tds at 1.5% on the same and now on 1st sep 2021 the remaining work has been completed and bill raised of 150000 and balance 75000 is payable, shall I deduct tds at 2% on whole 150000, is it legitimate and if there any liability of penalties late fees and interest will arise on the same...plz guide