Rotordriver,
I would assume that is the Medevac 214 gig in the Philippines with Evergreen that you refer to.
If so...and one retains a residence in the USA....you will find the IRS will soon separate you from some of that hot cash to which you refer. Whether you pay Social Security or not will depend upon how and who pays you. If it is Evergreen in McMinnville....you better get your purse open. Your first 80,000 USD will be tax liable if you remain out of the country for less than the required number of days and do not establish a bona-fide overseas residence. Anything over that amount is taxed. (Unless the tax law has changed since a few months ago.) If you are an Independent Contractor then you have other expenses to bear that detract from that sum. I assume you have Workman's Comp, Short Term/Long Term Disability Insurance, Ex-patriation and Medical Insurance? The other thought is whether you have the necessary work credit with the Social Security Administration to qualify for Retirement, Disabililty, Medicare, and/or Medicaid when the time comes. That working overseas is fine but one has to either make a large wad of money that will take care of your retirement and self funding of medical care in your old age or have a retirement plan that accomodates all that.
If it is Evergreen some things are certain. No benefits and no expectation you will be anything more than a temporary employee at which point you will be on your own even more so than you are now with them.
The Major downside to that gig is Evergreen itself....and that is a thread unto itself.
Note....
Your friend can re-claim excess Social Security deductions and excess income tax when he files his Federal Income Tax. That 120 USD deduction includes Federal/State income tax along with Social Security and Medicare deductions and some other deductions too I am sure.