Answer: $15,000
Step-by-step explanation:
As of December 31st 2017, eligible tax paying Sole proprietors are allowed to deduct up to 20% of their Qualified Business Income (QBI) from their domestic business. This also applied to QBI from domestic partnerships, S corporation, trust or estate.
For owners of the business, the QBI deduction is net of itemized deductions so with Tammy owning the business, her qualified QBI is;
= 20% * (100,000 - 25,000)
= $15,000