486.4. The recipient shall include, in computing the recipient’s income for the taxation year or fiscal period in which the original amount was paid or became payable or receivable, the amount by which the eligible portion of the specified amount, determined under section 486.9, exceeds the portion of the original amount that is included because of section 89, or that is not deductible because of section 144, in computing the income of the recipient for the taxation year or fiscal period.