Thanks –  I saw that same explanation on Google, but the source is pdffiller.com, and I don’t really consider them to be an authoritative source. I was unable to find similar wording on the IRS website. 

Prior to this particular situation, I’ve never had a client tell me that they received a form 433-D from the IRS in order to complete their installment plan.

Having said that, my research was somewhat limited because it was at the end of a very long day.