The introduction of the Tax Cuts and Jobs Act (TCJA) triggered the IRS to majorly revise the federal W-4 back in 2020. Among a number of changes, the most significant was the removal of federal withholding allowances.
This change posed a challenge to states that relied on the federal Form W-4 for their own state withholding. As a result, many states revamped their state withholding forms and began requiring taxpayers to submit both a state and a federal withholding form to ensure their state income withholding is accurate. But, it depends on the state. In some cases, just the federal form will do the trick.
Click the image below to download a handy chart summarizing W-4 requirements by state. Just remember, state requirements change often so you should always double check this information against your state's Department of Revenue website.