In past years, I have included the Form 2210 penalty in the amount owed on the return if it is more than $100.  IRS for decades hasn't assessed it, if it's less than that amount.  This year, on some returns where it was less than $250 or so, I omitted it and told clients to expect a bill only if there were enough people running the IRS computers to let the mail go out and then answer questions about it when people called.

Well, a client just told me that the bill for $138 has been received.  And it seems to me that IRS is being more efficient about it, because usually you wouldn't see these until July. Every dollar counts, I suppose, when you owe five trillion of them.