What is the normal annual salary for an Active Duty E-4 after taxes?

Go online to the Army Times- go to paycharts, look it up. All pay is normal, only allowances are different- and that will very from Post to Post/area. Also depending on allowances, some may be non-taxable. It is normal in the business world to ask for gross (before taxes) or net- you would do better with gross- due to the different state taxes.

This is the best web page i have seen that estimates your basic pay, BAH and BAS benefits based on pay grade, years of service and location (zip code).
https://www.federalpay.org/military/calculator?grade=O-5&years_experience=Over+22+&year=2017&zip=76310&is_dependent=1&annualize=0&service=Air+Force

When you calculate your pay, you will see the taxable portion of your pay, this is your basic pay. You can go to https://smartasset.com/taxes/paycheck-calculator and use this tool to calculate your taxes on your paycheck. Remember, you do not pay taxes on money from BAH and BAS.

One should not forget to figure the tax situation when comparing. Much of military compensation is not taxed. It can make a big difference.