Income Tax Liability refers to the amount of tax that is payable on your income.
When you do a tax return, you are figuring out two things:
- What is the income tax liability?
- What is the total of payments? (payments include taxes withheld, estimated payments, and tax credits)
The tax liability is compared to the total payments and you either get a refund, or owe additional tax.
"Effective tax rate percentage" is your tax liability divided by your total income. It has no direct relationship to whether you owe additional taxes.