For example, at my 25% Fed and 9% State tax rates, the current 4.14% rate for a 4-week T-Bill is the equivalent of a 1-month bank CD earning 4.70% annualized.
Note: The above calculator does not assume that you will itemize deductions and deduct your state taxes from your federal taxes. Even if you do itemize, I would note that everyone gets the standard deduction, so it’s not necessarily fully deductible.
Recent T-Bill auction results
2006 Federal Tax Rates
State Income Tax Rates