The Lemon Fool

Over past few yrs Ive put a bit away in a regular savings account to pay for next yrs holidays used to start them on 1st of a month then pay in every month on the first - just realised its actualy more sense to start them on the last day of a month , then you can put in the max ammount per month , on the last day of month , then make another deposit the following day. didn't think it would make a lot of diffrence , but on a 4,25% reg saver starting on the last day can actualy earn you just under £10 more interest as you have a longer period with the maximum balance in the account

I'd like to see the arithmetic that shows your result.

No arithmetic required:

Open account on the 25th of the month, and the first payment in earns 12 months interest.
The second month's deposit on the 1st then earns 11 months +24 days interest.
Third month earns 10 months+24 days interest etc.

Open account on the 1st of the month, and the first payment in earns 12 months interest.
The second month's deposit on the 1st then earns 11 months +zero days interest.
Third month earns 10 months+zero days interest etc.

Assumes the account works on a calendar month basis, some may but not sure most do.

"Your month is calculated by the date that you open your Regular eSaver, e.g. you open the Regular eSaver on the 16th of a month, your month will run from 16th of one month to the 15th of the next month." https://www.santander.co.uk/personal/savings-and-investments/savings/regular-esaver