Say someone gives me $90k in cash and I put it in my checking account. How much and for how long do i pay tax

[Judy]

If your checking account draws interest, then you'd pay tax on the interest for as long as you get interest.

Any other taxes depends on why they gave it to you. If it's just as a gift, then you don't pay income tax on it, although they would have to file a gift tax report, and they might or might not have to pay a gift tax. If they gave it to you for some kind of work that you performed for them, then it would be subject to income tax and self-employment tax in the year you received it.