Additional fees and amendment of return

If any executor or administrator has, through mistake or misapprehension or otherwise without fraud, omitted out of such return any part of the personal effects or estate of the testator or intestate, such executor or administrator may at any time within three calendar months after the discovery of such omission amend his return, and pay the additional fees or duties due on the estate of the deceased, without being liable to any penalty or forfeiture under this Act.