Estimated taxes and withholding in retirement

During working life, tax is withheld automatically. In retirement, the responsibility shifts, and the rules are specific enough that mistakes are common.

The requirement

Tax is generally due as income is received rather than at year end.

Where insufficient tax is paid during the year, an underpayment penalty applies, calculated as interest on the shortfall for the period it was outstanding.

The penalty is not enormous and it is entirely avoidable, which makes paying it an unnecessary cost.

The safe harbours

The rules provide defined thresholds that avoid the penalty regardless of the eventual liability.

Generally, paying at least a specified percentage of the current year's tax, or a specified percentage of the prior year's tax, satisfies the requirement.

The percentage based on the prior year is higher for taxpayers above a certain income level.

The prior-year safe harbour is the more useful of the two for most retirees, because the prior year's figure is known with certainty while the current year's is not.

Someone with volatile income — a large Roth conversion, a property sale, variable withdrawals — can simply pay based on last year's tax and avoid any penalty exposure regardless of what this year produces.

The withholding advantage

A useful technical feature.

Withholding is generally treated as paid evenly throughout the year regardless of when it actually occurs. Estimated payments are credited when made.

Which means a large withholding taken from an IRA distribution in December can cure an underpayment that arose earlier in the year, where an estimated payment in December could not.

This is a well-known planning technique and it is worth knowing about, particularly for anyone who realises late in the year that they are underpaid.

Where withholding is available

Social Security, at specified flat rates, requested using the appropriate form. Not withheld by default.

Pension and annuity payments, generally with withholding elected on a form.

IRA and retirement plan distributions, where a default withholding rate generally applies unless a different election is made.

Employer plan distributions eligible for rollover are subject to a mandatory withholding rate if paid to the taxpayer rather than transferred directly, which is one reason direct transfers are preferable.

Investment income generally has no withholding, which is where shortfalls typically arise.

Setting it up

The practical approach.

Estimate the year's total tax, subtract expected withholding, and cover the remainder either through additional withholding or quarterly estimated payments.

Many retirees find it simpler to arrange sufficient withholding from one source — typically an IRA distribution — to cover the whole liability, rather than managing four quarterly payments.

Where estimated payments are used, the deadlines fall on specified dates and missing one produces a penalty even if the annual total is correct.

The first year

Where errors concentrate.

The year of retirement frequently involves a partial year of wages, a possible severance or accrued leave payment, and the start of other income sources.

The prior-year safe harbour is particularly useful here, since the prior year was a full working year with substantial withholding already reflected in the calculation.

The second year is where the shortfall typically appears, because withholding from employment has ended entirely and nothing has replaced it.

State taxes

Frequently forgotten.

States with income taxes generally have their own estimated payment requirements and their own safe harbour rules, which may differ from federal ones.

Withholding elections on retirement distributions may be separate for state purposes.

The annual check

A short exercise worth doing in the autumn.

Compare tax paid to date against the safe harbour amount. If short, increase withholding on a remaining distribution.

Doing this in October leaves time to correct it. Discovering it in April does not.

The one-off events that catch people

Worth flagging specifically.

A property sale, a Roth conversion, a large capital gain, an inherited retirement account distribution or the exercise of stock options can each produce a substantial tax liability with no withholding attached.

The safe harbour based on the prior year's tax is the practical protection, because it does not depend on estimating the current year at all.

Where the event occurs late in the year and the prior-year safe harbour has not been met, additional withholding from a retirement account distribution is generally the fastest remedy available.

General information only, not tax advice. Rules, rates and deadlines change — consult a qualified tax professional about your own situation.