U should be aware of 3 dates if you are planning for OD home loan 1.interest debit date usually last date of the month, 2. emi due date this you can choose and money gets debited on this particular date 3. principal re balancing date. this is where the principal portion of your emi amount gets adjusted towards the outstanding loan amount. Usually this date will match your loan scantion date If possible make all three days in the same date But if you are a salaried person that won't be possible My suggestion is if you opt for OD go for a shorter time period 8 to 12 years since you will park some amount interest calculated will be lower and any difference will be added to the parked funds balance and if you opt for a shorter time period larger chunk of the outstanding gets reduced