I always thought the rule of thumb was that if a large lump sum outflow was needed immediately or in the very short term (~ 3 months), you should reduce the net investable assets by that amount. If the lump sum outflow was expected longer term (later in the year), then you can add that amount to your expenses needed for the coming year.
In Schweser Volume 2, page 89, it says "Betita will donate $750,000 to his alma mater over the coming year in one lump sum. I would think to add that to your year’s expenses. But the answer key says “Since the $750,000 will be donated within the next year, the total amount should be subtracted from the portoflio and not considered part of the investable asset base.”
Does anybody else feel that this is inconsistent with how CFAI does these questions?