What day of month does mortgage need to be paid by?

[Gonzalo Escobar]

I have a 6 conventional fannie mae back loans on my different 1-4 unit properties. The due date on my bills state the payment is due on the 1st of the month. When do I actually need to make the payment by to not incur a penalty? And then if for example I paid my loan serviced by citibank on the 5th vs the 1st of the month would I be charged interest for those 4 days beyond 1st?

Currently most of my rental income comes in around the 5th of the month so I have 5 day period were i get debited a huge amount for all the mortgages and then have to wait a couple days to get a corresponding rental credits.

[Fred Heller]

Mortgages usually have a grace period for the first 15 days of the month. Paying anytime during the grace period does not affect your credit score. Your score is only affected if you pay more than 30 days late. So if you miss paying by the 15th, you'll incur the late fee, but your account will be considered current as long as you pay by the end of the month. 

By the way, it should state somewhere on your monthly statement the last day you can pay without incurring a late fee.