An amendment of an income tax return filed by the taxpayer within the statutory period allowed for filing returns or within such extended time as the Commissioner may grant under the statute. J. E. Riley Invest. Co. v Commissioner (CA9) 110 F2d 655. An amendment of a pleading filed or served upon the adverse party within the time permitted for amendments by statute or rule of court, or, in the case of an amendment by leave of court, within the time fixed by the court. 41 Am J1st PI §§ 289, 296.