No action is necessary if the calculated under-withholding is less than $1,000.
Those most likely to under-withhold are married, single wage earning upper-middle-class taxpayers with two children, who itemize their deductions and report additional non-wage income like dividends and interest.
Under bonuses a provider is no worse off for not changing behaviour (they have simply forgone an extra payment), under withholds or penalties, a provider who fails to change is worse off: they must go through major changes just to maintain the status quo financially.
If you talk to patients with chronic conditions, you will find that the Veteran's Administration vastly under-treats, withholding medication and treatment that are used routinely in the private sector, but which the V.A. thinks are expensive or withholds for some other reason.
With the information that you get from Form 1040ES, you will have calculated the amount of under-withholding – if it turns out that you're over-withholding, you might make adjustments to your W4's or estimated payments as well, but that's another topic altogether.
A participating FFI that makes a withholdable payment not otherwise subject to withholding under chapter 3 or backup withholding under section 3406 to a recalcitrant account holder of a dormant account that it maintains must withhold on the account for purposes of chapter 4.
payor (as defined in § 1.6049-5(c)(5)) to an account holder of an account maintained by the FFI, when the payment is not subject to withholding under chapter 4 or to backup withholding under section 3406, and the conditions of paragraphs (c)(4)(i)(A), (B), or (C) of this section, as applicable, are met.
If a transfer of a U.S. real property interest described in section 1445 e) is exempt from withholding under the rules of this section, then no withholding is required under the general rules of section 1445(a) and § 1.1445-1.
A nominee responsible for withholding under the rules of this section shall be subject to liability under sections 1461 and 6655, as well as all applicable penalties and interest, as if such nominee was a partnership responsible for withholding under this section.
The central government is under fire for withholding information.
