According to the IRS, "Since the foreign earned income exclusion is voluntary,
qualifying individuals must choose to claim the exclusion."
[Source:
http://www.irs.gov/businesses/articl...82017,00.html]
Thus, you do not have to claim these exclusions if it helps you to save you taxes on your personal tax return.
But, on the other hand, if you choose to claim the "foreign earned income exclusion and the foreign housing cost amount exclusion" then you must determine these amounts using Form 2555 (pdf), which must be attached to Form 1040 (pdf).
But, also, it is worth noting that once the choice is made to exclude foreign earned income, that choice remains in effect for the year the election is made and all later years, unless revoked.