20 CFR § 345.121 - Jeopardy assessment.
(a) Whenever in the opinion of the Board it becomes necessary to protect the interests of the Government by effecting an immediate reporting and collection of an employer's contribution, the Board will assess the contribution whether or not the time otherwise prescribed by law for filing the contribution report and paying such contribution has expired, together with all penalties and interest thereon. Upon assessment, such contribution, and any penalty, and interest provided for under this part shall be immediately due and payable, and the Board shall thereupon issue immediately a notice and demand for payment of the contribution, penalty, and interest.
(b) The collection of the whole or any part of the amount of the jeopardy assessment may be stayed by filing with the Board a bond in an amount equal to the amount with respect to which the stay is desired, and with such sureties as the Board may deem necessary. Such bond shall be conditioned upon the payment of the amount (together with interest and any penalties thereon) the collection of which is stayed, at the time at which, but for the jeopardy assessment, such amount would be due. In lieu of surety or sureties the employer may deposit with the Board bonds or notes of the United States, or bonds or notes fully guaranteed by the United States as to principal and interest, having a par value not less than the amount of the bond required to be furnished, together with an agreement authorizing the Board in case of default to collect or sell such bonds or notes so deposited.