It should be noted that there is a reasonable cause exception to failure-to-deposit penalties for employment tax purposes, although IRS personnel sometimes suggest otherwise. I.R.C. §6656(a). It involves a showing that business cash flow prevented timely deposit of employment taxes. See, Diamond Plating Co. v. United States, 390 F.3d 1035 (7th Cir. 2004); Van Camp & Bennion Corp. v. United States, 251 F.3d 862 (9th Cir. 2001); Fran Corp. v. United States, 164 F.3d 814 (2d Cir. 1999); East Winds Industries, Inc. v. United States, 196 F.3d 499 (3rd Cir. 1999); QED, Inc. v. United States, 55 Fed Cl. 140 (2003); Schroer v. United States, 594 F.Supp.2d 1257 (D.Colo. 2009); Francis P. Harvey & Sons, Inc. v. Internal Revenue Service, 94 A.F.T.R.2d 2004-7258 (D.Mass. 2004). Especially interesting is Glenwal-Schmidt v. United States, 42 A.F.T.R.2d 78-5817 (D.D.C. 1978), which brings out the cash flow aspect nicely. The case law establishes that the analogy is to the reasonable cause exception to the general failure-to-pay penalty, so the only useful language from the regulations is found in the failure-to-pay regulations under I.R.C. §6651, e.g. Treas.Reg. §301.6651-1(c), in the absence of regulations under I.R.C. §6656. Proof of the claim, of course, is a separate matter.