3. I believe there are a few places in the tax code where there is a difference between having a full-time job and a part-time job, are there any areas where you would have to lie to the govt when you have multiple full-time jobs?
Assuming US-centric. The one that comes to mind is your W-4 for each employer. If you fill it out correctly, it will be a big red flag to your employer. If you pretend like you only have the one job, it could potentially land you in trouble with the IRS as there will be nowhere near enough tax withheld. You might get away with it, anyway, as long as you paid taxes in full and on time, but you might have to pay taxes in installments. They don't like you to owe too much at the end of the year.
I don't think the W4 is really much of a red flag. Someone with two jobs won't look significantly different from someone who has a high-earning spouse. Both will need to add additional withholdings to avoid underpayment.
Assuming US-centric. The one that comes to mind is your W-4 for each employer. If you fill it out correctly, it will be a big red flag to your employer. If you pretend like you only have the one job, it could potentially land you in trouble with the IRS as there will be nowhere near enough tax withheld. You might get away with it, anyway, as long as you paid taxes in full and on time, but you might have to pay taxes in installments. They don't like you to owe too much at the end of the year.