Does not normally receive more than a third of its support from gross in¬vestment income plus any excess of unrelated business taxable income over the tax on unrelated business income.
For purposes of (1) above, a substantial part of the foundation’s sup¬port generally is a third of its total support, based on a five year computation period that consists of the current tax year and the four years immediately preceding the current year. However, if the founda¬tion does not meet this one-third support test, it may still qualify as deriving a substantial part of its support from governmental units and from the general public if it