<prompt> Human: I am about a year into a 30 year mortgage with a fixed interest rate of 4.375.My mortgage payment is paid automatically on the first of each month from my checking account, so I am never late and never forget. I also have an extra 25 payment made automatically towards the principal on the first of each month. I have heard that paying even this little bit extra each month can you save you several mortgage payments down the road.My question:I do not earn a ton of money i am a public school teacher, but my wife and I live very frugally and live within our means. My wife does babysitting and tutoring every now and then to earn a little bit of money, and I also earn a few extra bucks from miscellaneous things here and there. Also, occasionally we have one or two hundred dollars extra left over in our budget if we under-spend over the course of a few months.Is it a good idea to throw any and all extra monies we come upon or are able to earn at the principal of the mortgage? I am talking about a few extra payments of anywhere in between 25 and 100 a month. The sad reality is that if we dont put this towards the mortgage, we probably will not invest it or do anything else other than let it sit in the checking account. In other words, will paying off even little amounts at a time be worth it in the end? Or is it so nominal that its not even worth it?Assistant: Is it a good idea to throw any and all extra monies we come upon or are able to earn at the principal of the mortgage?This all depends on your financial situation.Do you have an emergency fund?Do you have a house repairmaintenanceupgrade fund?Do you have any other outstanding debt?You said yourself, youre likely not going to invest this money elsewhere and at the amounts youve mentioned, its likely not enough to do a lot with, anyway.What does the rest of your picture look like?Human: We do have a very solid emergency fund, enough to cover at least 6 months of expenses for our family if we lost all income. We dont have a separate emergency fund for other things like home repair, we just keep the one emergency fund in a savings account with like .8 interest or something.If I pay 100 towards the principal of the mortgage, is it essentially like investing 100 and getting a 4.375 return over 30 years because thats what the interest rate is on the mortgage?  <response>: investing 100 and getting a 4.375 return over 30 yearsIt depends on when you pay it. Youre in year 1? Itll have 29.5-ish years of 4.375 annual returns. E.g. 1001.0437529 346.18.Paying extra makes less and less of a difference on interest paid as the timeline advances during the loan, such that paying extra during the last year makes hardly any difference at all compared to extra payments made during the first year. 