26 C.F.R. § 2.1-25
Any additional tax, including the 1.1 percent amount imposed by section 511(i) of the Act, due on account of withdrawal from a construction reserve fund, or failure to comply with section 511 of the Act or the regulations in this part, is collectible as a deficiency. Interest upon such deficiency will run from the date the withdrawal or noncompliance occurs. The amount of any deficiency, including interest and additions to the tax, determined as a result of such withdrawal or noncompliance, may be assessed, or a proceeding in court for the collection thereof may be begun without assessment, at any time and without regard to any period of limitations or any other provisions of law or rule of law, including the doctrine of res judicata.
26 C.F.R. § 2.1-25