Bond yield: This is the annual yield of your municipal bond or bond fund.
Estimated taxable income: This is your total income, after exemptions, adjustments, and deductions. We use this, along with your filing status, to determine your marginal income tax rate. You can use last year's tax return as a guide to what your taxable income will be for the current year. Your taxable income can be found your income tax form 1040 or 1040A. Make sure to increase or decrease the amount to compensate for any changes to your current year's income.
Federal tax filing status: This is used, along with your taxable income, to determine your Federal marginal income tax rate. The table below lists the Federal income tax rates by income and filing status. We use this table to determine your marginal Federal income tax rate.

Filing Status and Income Tax Rates 2008 Caution: Do not use these tax rate schedules to figure 2007 taxes. Use only to figure 2008 estimates.
Tax rate	Married filing jointly or Qualified Widow(er)	Single	Head of household	Married filing separately
10%	$0 - 16,050	$0 - 8,025	$0 - $11,450	$0 - 8,025
15%	$16,051- 65,100	$8,026- 32,550	$11,451- 43,650	$8,026- 32,550
25%	$65,101- 131,450	$32,551- 78,850	$43,651- 112,650	$32,551- 65,725
28%	$131,451- 200,300	$78,851- 164,550	$112,651- 182,400	$65,726- 100,150
33%	$200,301- 357,700	$164,551- 357,700	$182,401- 357,700	$100,151- 178,850
35%	over $357,700	over $357,700	over $357,700	over $178,850

Source: http://www.irs.gov/pub/irs-drop/rp-07-66.pdf

State income tax rate: Your marginal state income tax rate, if any.