What situation may require an individual to file a new W-4?

Filing a new W-4 may be necessary when there is a significant change in an individual's financial or personal situation that impacts their tax withholding needs. A large tax refund typically indicates that too much tax has been withheld throughout the year. This surplus arises when an individual’s withholding allowances do not accurately reflect their actual tax liability.

By adjusting their W-4 form after receiving a large tax refund, an individual can reduce the amount of tax withheld from their paycheck, which can result in having more disposable income throughout the year rather than waiting for a refund after filing taxes. This adjustment helps align tax withholding more closely with expected tax liability, making personal financial management more effective.

In the context of the other options, while improvements in the stock market or inheriting money can impact finances, they do not necessarily lead to immediate changes in taxation that require a new W-4. Getting a promotion can also alter tax situations, especially if it leads to increased income, but it's the large tax refund scenario that most directly suggests a need to reassess withholding.