A taxpayer can elect to deduct sales tax rather than state and local taxes. This election primarily benefits those who live in states that do not have a state income tax. However, the election is available to everyone.
The parents reduced their taxable income by $1,000 by electing to deduct their sales tax rather than state and local taxes. Since the parents income was taxed at the 30% tax bracket, the income reduction may decrease their income taxes by $300 ($1,000 x 30%).
If you are in a combined (federal, self-employment, and state) tax bracket of 30%, you could reduce your taxes up to $300 for every $1,000 of income reduction by electing to deduct your sales tax rather than state and local taxes.