Mass. Gen. Laws ch. 62C § 24
For the purpose of verifying any return filed under this chapter, the commissioner or his duly authorized representative may at any time within three years after the date prescribed for filing the return, or the date filed, whichever is later, examine the books, papers, records and other data of the taxpayer which shall be open to such person for verification. The taxpayer shall provide to the commissioner all accounting records and information in a searchable electronic format, as requested by the commissioner, to the extent that the taxpayer maintains such records in electronic format.
Stocks of unused stamps in the possession of stampers, as defined in section one of chapter sixty-four C, shall be open to inspection by the commissioner or his duly authorized representative at all reasonable times.
If the books, papers, records, and other data of the taxpayer are so voluminous as to make a complete audit thereof impractical and inefficient, the commissioner may use such statistical sample methods in conducting such audit as may be agreed to by the parties and project the audit findings derived therefrom over the entire audit period to determine the proper tax. If, after a good faith effort, the parties cannot reach such an agreement, the commissioner may utilize such statistical sample methods which he deems appropriate and which comply with the provisions of the Internal Revenue Code.
Mass. Gen. Laws ch. 62C, § 24