Agricultural Bank Assistance Act of 1986 - Amends the Federal Deposit Insurance Act to permit an agricultural bank to amortize over ten years any loss on a qualified agricultural loan that the bank would otherwise be required to show on an annual financial statement for calendar year 1986, 1987, or 1988. Disallows such amortization if the appropriate Federal banking agency determines that: (1) fraud or criminal abuse by the bank led to such loss; (2) the bank's capital-to-total financial assets ratio is less than three percent; or (3) the bank has failed to make good faith efforts to design a recapitalization plan to strengthen its capital-to-total financial assets ratio.