Several provisions in the Republican tax plan could significantly shift the financial landscape for school districts, many of which have long struggled to provide high-quality education while constrained by limited public dollars.

Both the House and Senate tax bills would sharply curtail the deduction for state and local taxes, often referred to as SALT, which run highest in states such as New York, New Jersey and California. The bills cap property-tax deductions at $10,000 and give no break for state and local income or sales...