Does IRS still average withholding payments over the tax year?

[Quentin818]

In past years, IRS had a “policy” of averaging wage withholding over the year so that, if someone realized he had too little withheld, he could increase at the end of the year and avoid an underpayment penalty (yearly OR “quarterly”). I am aware that IRS pubs say one needs to have withholding based on quarterly earnings but that does not mean they enforce this (and who knows what the statute says).

[Critter-3]

ALL withholdings are considered as being done ratably thru out the year  UNLESS you choose to enter them on the 2210AI form as being withheld when they were actually withheld.   Quarterly estimated taxes are NOT considered withholdings.  https://www.irs.gov/pub/irs-pdf/i2210.pdf

[Critter-3 · Accepted solution]

Making up  for under withholdings/estimated payments  by increasing the withholding from jobs/pensions/etc at the end of the year is a legal way to avoid the underpayment penalty.