Mortgage overpayment

DueNorther

Maybe a daft question but here I go if someone can help me. 

I have a mortgage split into two sub accounts (initial amount 180k @ <2% interest) which was from a previous property that I ported across in November. I borrowed an extra 40k @ 4.5% interest, which is the sub account. 

I moved in November and expected December to be the first payment, but it wasn't taken until January. Therefore I have the 'extra' December payment available and think it might make sense to overpay.

My question is do I overpay on the higher amount with less interest OR do I overpay on the smaller amount with the higher interest? OR do I split across both? 

The larger amount was a 5 year deal which ends in September 2025 and the extra borrowing is a 2 year deal ending December 2026. So I know % wise it will be going up.  

Mortgage advisor thinks tackle the smaller amount first (snowball effect). But, I was thinking it would make more sense overpaying on the bigger amount to get it down as it's on a better interest rate which will go up come September, so the more I can pay off the better surely?

It's not much, but as the saying goes, 'every little helps'.

Any help would be much appreciated. 

Thanks

Typhoon2000

Unless the follow on  rate on the first part is going to exceed the 4.5% ( and by some margin as you still a a good few month at the lower rate) on the second part I would overpay the 4.5% first. But you don’t know what the follow rate is going to be.

Hoenir

Highest interest rate first. If it's an option . 

DueNorther

Yes, we don't know what the follow rate will be although it will be considerably higher at probably around the 4.5% mark too unless things really change over the next few months. I will look at overpaying the higher interest rate first. Thanks both.