SEC. 2.. Section 319 of the same Code is hereby amended to read as follows:
"SEC. 319. Exceptions as to period of limitation of assessment and collection of taxes.— (a) In the case of a false or fraudulent return with intent to evade tax or of failure to file a return, the tax may be assessed, or a proceeding in court for the collection of such tax may be begun without assessment, at any time within ten years after the discovery of the falsity, fraud, or omission: Provided, That in a fraud assessment which has become final and executory, the fact of fraud shall be judicially taken cognizance of in the civil or criminal action for the collection thereof.
" (b) If before the expiration o£ the time prescribed in the preceding section for the assessment of the tax, both the Commissioner and the taxpayer have agreed in writing to its assessment after such time, the tax may be assessed within the period agreed upon. The period so agreed upon may be extended by subsequent written agreements made before the expiration of the period previously agreed upon.
" (c) Any internal revenue tax which has been assessed within the period of limitation above-prescribed may be collected by distraint or levy or by a proceeding in court within three years following the assessment of the tax.
" (d) Any internal revenue tax which has been assessed within the period agreed upon as provided in paragraph (b) hereinabove may be collected by distraint or levy or by a proceeding in court within the period agreed upon in writing before the expiration of the three-year period. The period so agreed upon may be extended by subsequent written agreements made before the expiration of the period previously agreed upon.
" (e) Provided, however, That nothing in the immediately preceding section and paragraph (a) hereof shall be construed to authorize the examination and investigation or inquiry into any tax returns filed in accordance with the provisions of any tax amnesty law or decree."
