(1) Assessment 
The amount of any penalty under section 6694 (a), section^[2] 6695, or 6695A shall be assessed within 3 years after the return or claim for refund with respect to which the penalty is assessed was filed, and no proceeding in court without assessment for the collection of such tax shall be begun after the expiration of such period. In the case of any penalty under section 6694 (b), the penalty may be assessed, or a proceeding in court for the collection of the penalty may be begun without assessment, at any time.

(2) Claim for refund 
Except as provided in section 6694 (d), any claim for refund of an overpayment of any penalty assessed under section 6694, 6695, or 6695A shall be filed within 3 years from the time the penalty was paid.

(1) Return 
The term return means any return of any tax imposed by this title.

(2) Claim for refund 
The term claim for refund means a claim for refund of, or credit against, any tax imposed by this title.