You can use the calculation method only if you elect to do so. You must then apply it to all interests in a particular FIF. If you subsequently use another method for the same FIF interests, you cannot use the calculation method again for that FIF or any interests you acquire in that FIF in the future. [section 535]
If you make an election to use the calculation method, you must also elect to use the period for which the FIF makes out its accounts as its notional accounting period. [subsections 486(3) and 535(5)]
The first notional accounting period of the FIF for which you use the calculation method may be for a shorter period than the period for which the FIF makes out its accounts. In this case, you will work out FIF income for the entire period for which the FIF makes out its accounts and apportion the resulting FIF income on a time basis.