Maximum value of financial account in FBAR

'Max Value' is the highest value the account reached during the year. Technically speaking, that should be in USD-equivalent value, not the maximum local-currency value.

Maximum Value is the highest value (in USD) reached in a given account during a year.

This most likely is the maximum value in local currency, but if the exchange rates changes significantly throughout the year, you have to provide the number that is the highest when the amount is converted to US dollars at the prevailing rate on that day.

Finding this maximum value involves a painstaking exercise of going through each months' bank statement and finding the highest daily balance (and converting it to USD).

In the case of a mortgage, if the mortgage was paid directly from your bank to the seller of the house your balance (of your mortgage account) would be negative. On the FBAR, for negative balances you would put zero.

However if the money (or a large amount, such as the deposit money) went through your checking account in that country, that would likely result in a larger positive number that has to be reported.