Relief for corporate minimum tax where past-year APA or secondary adjustments increase book profit, reducing tax payable accordingly. Relief reduces tax payable under sub-section (1) of section 115JB where past year income from an APA or secondary adjustment is included in current year book profit, using a formula that nets tax on book profit including and excluding past income and adjusts for aggregate tax on the original past years before and after inclusion; negative results are treated as zero. The relief reduces the section 115JAA tax credit by an equal amount, and must be claimed electronically in Form No.3CEEA with authorised verification and system filing procedures specified by the tax systems authority.