Getting Your W-4 Withholding Right
The goal is a small refund or a small bill, not a big one either way.
At a glance
Figures checked 1 Sep 2026
Time needed
30 minutes
Effort
Moderate
Have to hand
Recent payslips and last year's return
What you get
Cash flow through the year instead of a lump sum in April
What to take away
- Update the W-4 after marriage, a birth, a second job or a large income change.
- Two-earner households commonly under-withhold without the multiple jobs adjustment.
- Safe harbour rules protect you from underpayment penalties if you meet the thresholds.
Withholding is an estimate of your annual liability collected in instalments. A $4,200 refund means roughly $350 a month was unavailable to you all year for no return.
When it goes wrong
- Two earners, each withholding as though their income were the household’s only income.
- Significant self-employment or investment income alongside a salary.
- A mid-year job change with different pay levels.
- Life changes — marriage, divorce, a new dependant — not reflected on the form.
The IRS publishes a withholding estimator. Run it mid-year rather than in December, when there is still time for the remaining paycheques to correct the position.
Common questions
It is not harmful, just inefficient. Some people genuinely prefer it as forced saving, which is a reasonable behavioural choice rather than a financial one.