All the information that you provided is from your federal tax return, not your New Jersey tax return. TurboTax does not calculate an effective tax rate for New Jersey.
The figure that TurboTax calls "effective tax rate" is based on Adjusted Gross Income (AGI), not taxable income. It makes adjustments in its calculation for a number of uncommon situations. Try dividing the tax on Form 1040 line 16 by your AGI on line 11 and see if you get 6.15% or something close to it.
UPDATE: Instead of using the tax on Form 1040 line 16, try using the total tax on Form 1040 line 24. That should get you closer to the effective tax rate that TurboTax calculated.
I'm not sure what you mean by "the progessive taxing method," but the tax brackets apply to taxable income, not AGI. So you cannot compare the effective tax rate, which is based on AGI, to the tax brackets that apply to taxable income. The effective tax rate has nothing to do with the rates that are used to calculate your tax. The effective tax rate is just meant to give you a bird's eye view of what percentage of your total income you are paying in federal income tax. That also means that you cannot use the effective tax rate to estimate your 2024 tax.
You said "I am trying to calculate our Estimated 2024 income." TurboTax can't estimate your income, and the effective tax rate doesn't tell you anything about your expected income. You have to figure out how much income you expect to have from your various sources of income. If you mean that you want to estimate your 2024 tax, there are various ways to do that once you have an estimate of your 2024 income. One tool you can use is TaxCaster. It's still set up for 2023, but there are not likely to be any major changes for 2024, so it will give you a good rough estimate of your federal tax. You didn't say whether you are using TurboTax Online or the CD/Download TurboTax software for 2023. If you are using the CD/Download software you can use the What-If Worksheet in forms mode to estimate your 2024 tax. It has a box at the top of each column that you can check to use 2024 tax rates.
