If you plan to maintain your Illinois residency, you would simply keep your house in Illinois as your main home, and not register to vote in GA or register you ca and get a new driver's license in GA.

You will likely have state tax withheld for working in GA and will file a nonresident state return there.  You will file a resident return in IL and will take a credit there for tax paid in GA.  You can no longer take living expenses in GA as a job-related expense, so it does not matter if the job lasts less or more than a year.

If you plan to maintain your Illinois residency, you would simply keep your house in Illinois as your main home, and not register to vote in GA or register you car and get a new driver's license in GA.

You will likely have state tax withheld for working in GA and will file a nonresident state return there.  You will file a resident return in IL and will take a credit there for tax paid in GA.  You can no longer take living expenses in GA as a job-related expense, so it does not matter if the job lasts less or more than a year.

You should only be liable for state taxes in the state of your official residence (where you register to vote, address on your driver's license). If your company takes out state taxes where they are located or where you may be temporarily staying, you should file for a refund in that state. I worked with telehealth patients in WV and my employer there took out taxes. I live in FL with no state tax. TurboTax erroneously DID NOT direct me to seek a refund on this amount and I pad for taxes for 2.5 years. I did get 1.5 years of it refunded after much ado...but be cautious as this interstate stuff is not a strong suit of the Turbotax platform. There are some rare exceptions where taxes may be owed where one works but not lives (NY has some laws about commuters) but most of the time, you are only responsible for taxes in the state of your residence.

There are a few states which levy taxes on those who live there and work remotely elsewhere but you should be aware that TT is not very savvy about these laws. Best look into them yourself.