There is a distinct and real difference between a Factoring Fee and an Annual Percentage Rate when discussing the price of interest on a loan. Comparing the two is like saying that an all season radial tire is the same as a bicycle tire. They are both round, made of rubber, help you get somewhere, but not interchangeable. Therefore multiplying a 30 day invoice discount fee by twelve does not reflect a reasonable figure.
When a factoring company makes an advance on a 30 day invoice, we expect to be repaid somewhere well within a 90 day time frame, usually between 27 and 45 days. This means the risk involved is over a short period of time. This allows the factor to make quick adjustments accordingly. This short leash is reflective of the risk the borrower brings into the equation. A bank on the other hand will make a loan that they expect will be paid over a year or more. They are making a calculation that your business will be the same or better over that period of time. If there is a risk that you might not be able to pay back the loan, no loan.
With factoring invoices, the decision to advance funds is primarily based on the creditworthiness of the debtor. It is your customer who will repay (pay off) the advance. So if you try and compare an annualized rate with a short term rate, you must at the same time compare a company that can qualify for a long term loan and one that cannot. Those two companies are not the same, neither is the cost of funds.