So I've been making payments to my auto loan for a little over a year now (my first purchase).

I'm on a simple interest loan and I'm curious to know how amortization works. Looking at a few calculators online, the obvious is that as you pay down your loan, a chunk of it goes to your principal, a chunk of it goes to interest.

The other obvious pattern is that as you constantly make your payments, the amount you pay in principle increases, and amount you pay in interest decreases.

I'm looking at my history from my credit union for the past 12 months and it seems like the amount they take out from principle and the amount they take out in interest per month seems to be all over the place. This is where my confusion is.

Example:


Is this normal?

Depending on the day of the month when the payments are made would be my quess.

Example: you pay the 5th of this month when payment is due on the 28th.

Next month you pay on the 25th and you have 20 more days of interest than you did last month

The payments have been made (on time) on the same week it is due (give or take a few days).

Have you paid any extra? Any extra (if current on loan should apply to principal).

Your info there is confusing. Each month the amount applied to principal should increase, and each month the amount of interest should decrease. (Not that dramatic though).

Give or take a few days can make a significant difference. Can you post the dates for the payments above?

Every payment I am adding $25 extra. And yes, it is confusing as to why principle/interest is all over the place.

Here's a revised chart including due date and paid date:

You do have some odd numbers there. Normally, if you take the interest paid for each period, divided by the number of days in the period, that amount will decrease steadily as the loan is paid off. Your interest for payments 7, 8, and 9 make sense. Interest for payment 6 looks too high, and 5 looks too low.

Thanks. A good bulk of it still does not make sense to me but since I gotta drop off a payment this week, I think I'll talk to someone at the CU about this whole ordeal.

It doesn't make sense because those numbers are simply not correct. Hold them to account, and let us know what they say. That's a curious case.