If I go to school, my company will pay me an extra $5k as tuition assistance. Can I still take a $5k distribution from my 529, or will I only be able to take distributions after the $5k mark?
You can't pay for tuition with tax-free money and also take a tax-free withdrawal.
If the total tuition is less than or equal to the tax-free reimbursement, then you can't take a tax-free 529 withdrawal. Any withdrawal would be considered non-qualified.
If the tuition reimbursement is taxable, or the total tuition is more than tax-free reimbursement, then you can take a 529 withdrawal to cover the difference and it will be tax-free.
My son seems to think that by providing a receipt of 529 payments (I made) to the University, that he can take that and file it as "paid education" and get "reimbursed" from his employer. Clearly, I'm using quotes to emphasize that he himself didn't pay for education and so wouldn't qualify to get reimbursed, but I wanted to make sure I'm not missing something here? To me this sounds unethical.