Which of the following cannot be a valid filing status for claiming the standard deduction?

The valid filing statuses when it comes to claiming the standard deduction include options such as married filing jointly, single, and head of household. All these statuses allow taxpayers to claim the standard deduction, which is a set amount that reduces the taxable income.

However, when it comes to the scenario of married filing separately, there's a crucial detail to consider. If one spouse is itemizing deductions, the other spouse must also itemize their deductions, even if their itemized deductions would be less than the standard deduction. This means that if one spouse chooses to itemize while the other is filing separately, the latter cannot claim the standard deduction. This condition is put in place to prevent any potential tax manipulation between spouses, ensuring fairness in the tax system.

Thus, the option regarding married filing separately with a spouse itemizing deductions accurately reflects a situation where the standard deduction cannot be claimed, making it the correct choice in this context.