If you own a large home and you want to refinance it, or you’re looking to buy a luxury property or a large apartment downtown, you’ll find yourself in the predicament of looking at typical 15 year jumbo mortgage rates. For a number of reasons, loans over a certain size attract higher interest rates, and this is especially true after the global financial crisis.

A ‘jumbo’ mortgage is a loan that is over $417,000. It’s called jumbo because this is the largest size that the two largest buyers of mortgages, Fannie Mae and Freddie Mac, will buy from your bank. Banks frequently sell their mortgages on to larger investment banks like this because this frees up more of their capital to lend out to new customers. Because Fannie Mae and Freddie Mac will not buy these loans, the average 15 year jumbo mortgage rates are a little higher than the average.

The legal limit is actually $729,750, but since loans above the original limit attract the higher interest rates anyway, most banks still enforce the lower limit. This means that if you’re trying to find a jumbo mortgage you’re going to have to be in excellent credit standing, be prepared to pay slightly higher interest rates, and be will to shop around for the best rates you can find.

If you already own a property, however, and you’re looking to refinance it, you also need to look out for the best deal. You’ll have to shop around to find the best 15 year mortgage rates. Refinance on jumbo loans comes at a slightly higher interest rate, so you could end up with the capital that you need, but at a cost that isn’t sustainable on a monthly basis.