S.2389: A bill to amend the Internal Revenue Code of 1986 to increase the alternative minimum tax credit amount for individuals with long-term unused credits for prior year minimum tax liability, and for other purposes.

Amends the Internal Revenue Code to: (1) increase the alternative minimum tax (AMT) refundable credit amount for individuals who have long-term unused minimum tax credits from prior taxable years; and (2) abate any underpayment of tax attributable to the application of special AMT rules for the treatment of incentive stock options.