@Opus 17 wrote:
Nevertheless, because the system is self-adjusting, it is unwise to claim exempt, especially if someone's income is variable.
It is just the opposite.
Common scenario: A full-time student does minimal-to-no work during the school year. They work hard during the summer. Let's say the student has $1,000 of income each week for 12 weeks of summer, and no other income during the rest of the year. In that common scenario, the student would not owe tax and therefore can be exempt. But the W-4 assumes he earns $1,000 a week for 52 weeks, so unless he claims exempt, tax is withheld when there is no need to do that.
