Credit
If you need money, you can go to the bank and propose for a credit. Your bank allows you a certain sum of money (calls credit limit) and will transfer the purposed sum directly on your account then. You have to pay interest for the lent sum. A credit stays a credit till the full settlement of the loan by the menu item "bank". Credits of the last season also remain in current season, even if your credit limit got smaller.

Overdraft loan
If your account shows a sum less than 0, you are in the overdraft zone. From this it follows, that a overdraft loan is not requested, but this means the overrun of your account under a balance of 0. Consequently the interest for a overdraft is higher as the interest of a agreed loan.

ATTENTION: All stated interest in the game are season interest. If you want to know how much interest you have to pay per day, divide the interestrate by 34 and calculate on with this percentage.
For example: 100.000 credit by 15 % interest = 100.000*15%/34=441 pound per matchday.

calculation of the credit limit
The credit limit is calculated as follows:
credit limit = (income - taken amount - transfer income - bet income) / 2 + 200.000

The credit limit is hereby always calculated with the values of the last season for the following season. It means, for this calculation only the income that is shown under "finances" on 34th matchday before the seasonbreak is important. So the credit limit stays the same at the hole season.

What happens if I goes insolvent?
In case of debt you haven't to be afraid on consequences like a withdrawal of licence or something else. There's no reason. You will not be relegated or banned for a negative balance. How far you can handle the debts and interest is a whole new ball game.