Is it legal to deduct salary for lateness under policy?

Hi, I’m a global HR manager in Korea, and I have an Indian subsidiary where lateness is frequent. I’m considering a late penalty policy where employees get warnings for up to 3 instances of lateness per month, and salary deductions will apply for more than 3 instances, proportional to the time late. I’d like to know if it’s legal to deduct salary this way and whether we can replace the clause in the employment contract with a separate "consent for deduction" document to avoid contract revisions. Thank you for your help!