OK here goes:

I've got a high interest current account with Halifax which pays me 6.05% gross (approx 4.8% net) on my balance. This interest is calculated on a daily basis and paid monthly at the end of each month. The idea behind this account is to keep as much money in the account for as long as possible.

I then also have an Egg Money Credit Card. This pays me 1% cashback on everything I buy using it. It also allows me to buy something now and pay in a months time. This Cashback is accumulated and paid annually.

Whenever I can use my Credit Card to buy something, I do. I never use Cash unless I have to because then you're reducing the balance that sits in the high interest current account and you'll also be losing out on the 1% cashback.

I have setup my monthly statements for the Egg card to the 2nd of the month which means that the full balance of the card is paid off on or around the 25th of the month. This is just prior to me being paid from work. Because nothing has gone out my bank account except for Direct Debits (which I also set to near the end of the month) it means that I have a high balance sat in my current account all month (except for a couple of days between when I pay my credit card bill and when i get paid).

Examples:

If you were paid £1000 a month into your current account and it sat there all month then you would receive £3.90 interest in a 30 day month.

Then if you spent £500 on your Egg Money credit card during the month you would have received £5 in cashback for that month.

So in total you would have earned £8.90 for that month. That's £106.80 over a year.

Hopefully this makes sense.