What describes a taxpayer's tax liability?

A taxpayer's tax liability refers to the total amount of tax that must be paid to the government based on their taxable income and applicable tax rates. It encompasses various factors including income earned, deductions, credits, and other elements that determine a taxpayer’s final financial obligation to tax authorities. This total tax bill is critical in tax calculations, as it impacts a taxpayer's decision-making, financial planning, and compliance with tax laws.

The other options represent different concepts in the tax arena. For instance, the gross income amount before deductions is merely the starting point for calculating tax liability and does not reflect the final obligation. Similarly, net income after all deductions pertains to what remains after the deductions are applied but is not the same as the total tax due. Lastly, the estimated tax refund amount for the year relates to any overpayment of taxes, which is separate from the concept of tax liability itself. Hence, option B accurately encapsulates what tax liability entails.