A married couple filing jointly earns $40,000 and $60,000. What is their qualified business income deduction if the wife has a side business generating $45,000?

To determine the qualified business income (QBI) deduction for a married couple filing jointly, it's essential to understand how the QBI deduction is calculated.

The QBI deduction can be up to 20% of qualified business income. In this scenario, the wife has a side business generating $45,000 in income. Therefore, the QBI from her side business would be $45,000.

To calculate the QBI deduction, you take 20% of the business income. In this case:

20% of $45,000 equals $9,000.

This amount represents the potential deduction that the couple can claim based on the wife's qualified business income. It's important to note that other income factors, such as the couple's overall taxable income and any limitations that might apply to high income earners, weren't indicated to be relevant here based on typical structures for QBI, hence yielding a straightforward deduction amount.

Therefore, the qualified business income deduction for the wife’s side business is correctly figured to be $9,000, which corresponds to the answer choice.