I put a DC pension on the FBAR for the first time last year, and found it was virtually impossible to calculate the maximum value. Technically, the value fluctuates minute by minute with the financial markets. Even if you use the end of day values only, it gets complicated if there are any contributions or other transactions on the account. Just for completeness, I asked my pension provider (Standard Life) if there was any way they could calculate the maximum value for me but they were unable to accommodate the request. Given this predicament, I decided to check the box for "maximum account value unknown" on the FBAR. I figured, if Standard Life doesn't know the maximum value, there's no way they can pass it to the IRS.
Curious if others have done differently.