What is the meaning of taxable amount owed?

Do you mean the amount of taxes owed on one's taxable income?

When an individual or a married couple starts filling out federal income tax papers each year, they start with income from all their different sources. Once all that is added up, it's called the gross income. After all the tax deductions are itemized and subtracted, then there's the taxable income. That's the amount of money on which the actual amount of income taxes are calculated.