Hello! It is not necessary to update your W-4 every year, as long as there are no changes to your filing situation. Marriage, children, or big increase in pay or other income may constitute a change in the amount that you want withheld, but you can cross that bridge when you come to it. Hope this helps!
Hi, Taxin4Me,
You are not required to update your W-4 unless there are major changes to the tax law (as in the TCJA) or life changes. This is from the W-4 instructions:
Complete a new Form W-4 when changes to your personal or financial situation would change the entries on the form.
That said, there are many reasons you might want to update that W-4 (like income from a second job or a nice capital gain windfall). Check out this article for the top 5 reasons. Some payroll departments also require employees to update it annually.
Cheers!