If you are refinancing this applies to you. You need to enter the "balance" of your 1st mortgage (only) in this box. You can either go on line to get your mortgage balance from your existing mortgage company (such as Chase, Citibank, Wells Fargo, Bank of America or whoever is holding your first mortgage) or you can estimate it. Look at your mortgage statement that you receive on a monthly basis.... on that statement there should be an estimated mortgage balance, if so, enter that in this box. It's always good to know the balance of your existing mortgage or mortgages (if you have a 2nd mortgage).
With this "new" refinance the "new" mortgage company will obtain an accurate payoff for you from your existing mortgage company prior to closing. The payoff will tell the new mortgage company "how much" they have to payoff in order to obtain a brand new mortgage refinance. Knowing the exact number is almost impossible at the time of this mortgage prequalification however, the closer you can estimate the better qualified you will be for a new mortgage refinance.
You can always call your existing mortgage lender and obtain a payoff yourself but remember this cost money. How much depends on your lender. Always remember that your payoff includes the following:
Existing mortgage balance
Property Taxes (including back taxes owed)
Late Fees (if you were ever late on your mortgage and didn't pay the late fee the mortgage company adds that in the end)
Any homeowners insurance (fire insurance) that is due (including anything past due)
Payoff letters (yes, it costs money for somebody at Chase Mortgage to figure out what your payoff is and somebody has to pay for it and that is you)
So, for example you might think that the balance of your first mortgage is around $200,000 and if you estimate that here for a mortgage prequalification that is fine but remember that this is only an estimate. With all of the above fees the actual balance due to your existing mortgage company is probably more like $202,000.
Also, when you make a mortgage payment every month that payment is being made "in the rears" so you are paying this month for last months payment. Therefore, you live in the house THAN you make a payment.