Offer your thoughts or opinion on the input financial query or topic using your financial background.

Prepaying a loan: Shouldn't the interest be recalculated like a shorter loan?
Forget about terms.  Think about loans in terms of months.  To simplify things, let's consider a $1000 loan with .3% interest per month.   This looks like a ten month term, but it's equally reasonable to think about it on a month-to-month basis.  In the first month, you borrowed $1000 and accrued $3 interest.  With the $102 payment, that leaves $901 which you borrow for another month.  So on and so forth.   The payoff after five payments would by $503.54 ($502.03 principal plus $1.51 interest).  You'd save $2.99 in interest after paying $13.54.  The reason why most of the interest was already paid is that you already did most of the borrowing.  You borrowed $502.03 for six months and about $100 each for five, four, three, two, and one month.  So you borrowed about $4500 months (you borrowed $1000 for the first month, $901 for the second month, etc.).  The total for a ten month $1000 loan is about $5500 months of borrowing.  So you've done 9/11 of the borrowing.  It's unsurprising that you've paid about 9/11 of the interest.   If you did this as a six month loan instead, then the payments look different.  Say  You borrow $1000 for one month.  Then 834 for one month.  So on and so forth.  Adding that together, you get about $168.50 * 21 or $3538.50 months borrowed.  Since you only borrow about 7/9 as much, you should pay 7/9 the interest.  And if we adding things up, we get $10.54 in interest, about 7/9 of $13.54.   That's how I would expect your mortgage to work in the United States (and I'd expect it to be similar elsewhere).  Mortgages are pretty straight-jacketed by federal and state regulations.   I too once had a car loan that claimed that early payment didn't matter.  But to get rid of the loan, I made extra payments.  And they ended up crediting me with an early release.  In fact, they rebated part of my last payment.  I saved several hundred dollars through the early release.  Perhaps your loan did not work the same way.  Perhaps it did.  But in any case, mortgages don't generally work like you describe.