Whereas normal homeowners who live in their homes for years or decades on end may treat their home sales as capital gains, house flippers must report all of the income that they receive from their business activities as regular income. Although house flippers who hang on to a given property for more than a year may be able to claim the profit from its sale as capital gains, most flippers sell their homes within just a few months.
Law Dictionary: How Do I Report a House Flip on My Taxes?