I don't know if this is uncommon, but on both business checking accounts (in the US) I've set up, I asked for and got attached lines of credit. Basically, it le

I don't know if this is uncommon, but on both business checking accounts (in the US) I've set up, I asked for and got attached lines of credit. Basically, it lets you bounce above and below a zero balance in case your cash flow is tight. You could certainly use it to get yourself into trouble, but I didn't and it was very useful.