When should an individual or business file a SAR with FinCen? In the United States, both Individuals and Businesses are required to file a Suspicious Activity Report (SAR) with FinCen when:


Individuals who transport more than $10,000 into or out of the United States1
Shippers and receivers involved in the transfer of $10,000 into or out of the United States.
Businesses that receive more than $10,000 in a transaction or in related transactions1
People who have control over more than $10,000 in financial accounts outside of the U.S. during a calendar year


Question


How could these rules be interpreted when dealing with Bitcoin? (please contrast conservative and non-conservative viewpoints)
Since Bitcoin's value varies, does that mean that a declaration is required when the price exceeds a certain amount?
What is considered as "transporting" into and out of the United States?
Is simply running a Bitcoin QT client considered a "money services business" and is subject to FinCEN requirements?  If my wallet is hosted, does that mean they are responsible?
While bitcoin may seem to be useful as an offshore bank account, it likely won't be subject to the FBAR reporting requirements.

Now if you have fiat (e.g., USD) funds at an exchange that is not in your own country (e.g., Mt. Gox) and those funds exceed $10,000 worth then possibly that could be something where an FBAR filing might be required.

So having $10K or more at an exchange might be reportable but having $10K worth of bitcoins may or may not.  

An excerpt from someone who studies this topic:


  The critical issue is whether a wallet constitutes a financial account
  and if a wallet constitutes a financial account then what constitutes
  signature authority?