How do overpayments work?

Haywooddiablo

Hi all, I've got an HSBC mortgage (technically 3 mortgages for the one home), and can't get my head around how overpayments work, so have two questions:

1) I've overpaid by 10% on all mortgages this year. I was expecting to see the remaining term reduced, but do my payments remain the same, and the amount of interest just reduces!?

2) The fixed rate for one of my mortgages, ends on 31st Dec, so I've locked in a new rate now, but asked that it only takes effect on 1st Jan, so that I can maximise the lower rate for as long as possible! Now on the existing deal, I'm able to overpay again by 10% in November, before the new deal starts.
a) Is there anything preventing me from overpaying in Nov?
b) Would I be able to overpay again when the new deal starts? Not that I can probably afford as it stands, but want to be able to understand my product fully!!

Thanks in advance 

pinkteapot

To answer question 1....

Overpayments either: 
1) Reduce your monthly standard repayment, keeping the term the same
2) Reduce the term, keeping the monthly standard repayment the same

Different lenders apply one or the other by default. HSBC is #2. You can probably ask them to re-calculate your monthly payment to reduce it, but we never have.

We've overpaid with a few different HSBC mortgages over the years. It will be reducing the term - it has to be - you can see your capital owed going down faster, so it'll be £0 sooner. But they don't show you your remaining term anywhere. Where are you seeing it displayed? To my knowledge they don't re-calculate it for you, but there's calculators online you can use.

kandfs_mam

As far as I am aware with HSBC  the monthly repayment stays the same until there is an interest rate change when it is recalculated.