Travel therapy/accounting questions

[Guest guest]

I'm a contract therapist actually on my first " travel " assignment.

I'm getting per diem, mileage and housing based on info off of a

gsa.gov website. My taxable hourly rate is about a third of what my

actual hourly rate comes out to be. I'm doing a local travel

assignment which is about 64 miles one way. Will I get hit on my end

of year taxes on the money that is not being taxed on my weekly

paycheck? What governs the 50 mile rule? Is it an accounting rule or

is there an IRS publication that explains it? Does this same info

apply to independent contractors or just through an agency? If any

one can point me into the right direction so I can better understand

this, thank you ahead of time!

Thanks again!