so I do have to file an Fbar - if your personal non US bank, savings, & retirement accounts in the aggregate at any point in the year exceed 10K (USD) you have an FBAR filing requirement for that year. For example, let's assume you have 5,000 Canadian savings accounts with $3 in each account on March 17th, of 2011. You would have a 15,000 aggregate balance and you must report each account on an FBAR due June 30th 2012.
but I also have signing authority over a corporate business checking account - I own 2\3 of the company. - this would also create an FBAR filing requirement since you have signatory authority over a foreign bank account and your interest in the foreign entity exceeds 50% (i.e. you have control) Note that you probably have a Form 5471 filing requirement and potentially a Form 8938 filing requirement.
Does the maximum amount in this account go in part IV?? - yes the maximum value of the business account would be reported in Part IV line 15.
Do I use my last name or company name on line 6? - your personal information is reported on lines 1-6 of all Parts I-V. The business information is reported on line 34-42 of Part IV.
What about lines 34-43?? - The business information is reported on line 34-42 of Part IV. Report your title with the company on line 43.
I hope this helps. Let me know if you have any further questions.
the biz does not have a tax id # XXXXX a foreign id #, so what goes in line 35??? - generally you would put in "FOREIGNUS" or "N/A" or leave it blank.
Am I using the biz address for 35,36,37,38 etc...? - yes exactly, although 36 & 37 would be blank since it is a business.
Let me know if you have any further questions.