I am trying to create an equation that will increase an amount due on a loan base on the amount of time that has passed.

For example, a new loan, if paid within the first 6 months, has an interest rate of 40%. If it takes a person 7-12 months to pay back the loan, the interest goes up to 60%, 13-15 months 80%, etc etc.

I have attached a table as reference.

How can I calculate the Payout amount of a loan to increase based on the time passed since the original loan was taken out?

Thanks

Jason