Note:  If paying past 15 days late, a late payment fee is usually applied.   The lender will have specific requirements regarding when the late fee must be paid.

At 30 days and after, a late payment can be a big deal, depending what creditor is reporting it.   For example, if you want a house loan, it’s not beneficial to be late on a mortgage payment.   Banks looking to lend money for car loans don’t fancy seeing 30-day late payments for previous auto loans, etc.    It makes the lender feel insecure, to an extent, about how willing or able you are to pay back the loan.   If you’re late (past 30 days), they know you’re willing to let your payment slide, at least once.

I pulled my credit report a week or two ago.    Spotless.   Even though I’ve made a car payment or two a day or so late, this minor delay is not reported.   The bank just has the pleasure of receiving a $15 late fee from me someday.  

30-day+ late payments are only part of the picture.   I’m not an expert in improving credit scores, but these people seem to be.