To find out what your take home will be figure out how much you'll owe in taxes, and how much various insurance plans will cost and subtract that from gross. Say insurance is $100/month (no idea if that's accurate) and you max your TSP. So you'll have $97k -18.5k -1200 = $77.3k AGI. $77.3k - 12k standard deduction = $65.3k taxable income. Taking a look at 2018 tax brackets you'll owe $10.3k. So take home would be $97k gross - 10.3k fed tax - $1200 insurance - 18.5k TSP - some DC tax = $67k - DC tax. So you'll still need to figure out what DC tax will be, and what insurance and other benefits will cost. To make what you figure your actual take home you'll need to dial in your withholding, but at least after figuring in any tax payments/refunds you make/get at tax time to account for variation in withholding that's what your take home will be.

So here is what I've come up with

Gross = 96970 for year 1

Biweekly gross = 3729.61

No TSP eligibility for 12 months :(

IRA instead = 211 biweekly

Pension = 370 biweekly (I think they take 1%)

Insurance = ballpark , high estimate for health, dental, vision (I have some health issues, so will look for good coverage and will be using it) = 178 biweekly

FICA = 285 biweekly (7.65%)

Taxes = Fed = 22% of gross less everything except FICA-standard deduction of 12K = 14348 for the year (22% of 65220) or 551 biweekly

State (MD) = 3200 or $121 biweekly

There will be some commuter benefits that save on taxes a few hundred dollars, but I'm not calculating that

Union dues? I think these are automatic at $25 per pay period (could be per year, I can't tell, so conservative estimate = 25 per pay period)

Total take home = 1988 every two weeks. (my take home now is about 1500 biweekly). Seems low.

That would put a 1600 apartment at 35% of my take home, which seems like an awfully big chunk!

Did I do those calculations right, in a ballpark sort of way?

And yes, in response to the questions. I'm a SITC. Single income two cats. No SO. No other real tax deductions of note, either btw. I'm down to 3K in student loans and will pay that off soon.

Edited: forgot state income taxes, which if I live in Maryland would be about 3200 or $123 a check. updating above.