By my estimation and IRS calculator, his tax liability is probably under 20%. Probably. This assumes about 15% is being taken out for healthcare and retirement however, so yeah, the net paycheck will be approximately 30-40% lower than gross.
I’d estimate OP has $440 a month left over after all the list expenses.
Use this tax calculator; it includes FICA, state taxes, and local taxes:
https://smartasset.com/taxes/income-taxes
No one is paying 40% total tax rate unless they are single, make $350,000+, and live in a high tax area (NYC, San Francisco). If you are married, you have to make at least $800,000 to pay 40% overall.
That’s what I used. Still some question about how much nontaxable retirement/Healthcare as well as what the state taxes would be. I estimated $5,700 in federal and $1000 in state. Based on 10% to retirement and $2400 a year for insurance, right off the top, and a 3% state tax.