<<Try calling early in the day or late >>
the Inspector General's report stated that while hold times are much improved from last year, the IRS hasn't figured out how to match their employee on the phones with the ebb and flow of the call volume. As a result, there are agent waiting to take calls early and late in the day, while there is a backlog of calls in the middle of the day.
Another trick - and this goes for ALL 800- number call centers - avoid Mondays.....absentism tends to be higher and calls backlog as there are not enough employees to answer the phones
