The average federal refund runs around $3,000. Spread that across 26 pay periods and it's about $115 a paycheck you handed the IRS and got back a year later. No interest. The government doesn't pay you for the use of it.
Some people want it that way, and I don't argue with them much. If the alternative is $115 evaporating every two weeks with nothing to show for it, the forced-savings version wins. But it only wins if the refund gets used for something. If it lands in March and it's gone by April, you paid for the discipline and didn't get any.
The dial is the W-4, and it changed a few years ago. The old version counted allowances. The current one asks about other jobs, dependents, other income, and deductions, and then there are two direct lines near the bottom: extra withholding per paycheck, and a spot to claim exemption. Step 4(c) is the one that adds a flat dollar amount to every check.
Two-income households are where withholding goes sideways. Each employer withholds as though its paycheck is the only income in the house, which underestimates the combined bracket. The W-4 has a checkbox in Step 2 for exactly this, and the IRS runs a withholding estimator online that'll tell you what to put where. Twenty minutes with a couple of recent pay stubs.
Going the other direction has a floor you should know about. Underpay by enough and there's a penalty, but you're generally safe if you've paid in at least 90% of this year's tax or 100% of last year's, and 110% of last year's if your income is high. Hitting one of those safe harbors is the target, not landing at zero.
If you do dial it in, the extra money has to have somewhere to go the same day it shows up. Route it to the savings account or the debt payment before it hits checking, because $115 landing in a spending account gets spent. That isn't a character flaw, it's just what happens to money that sits where the spending happens.
Self-employed income runs on quarterly estimates instead, due in April, June, September, and January. Same math underneath, different form.
I'm a licensed insurance broker, not a CPA. If your situation has moving parts, have a preparer run the numbers before you change anything on the form.