[JoshTriplett]

Anecdotally, you can do so without both halves, as long as the piece you have is clearly the majority of the bill.

I don't know either the relevant law or common institutional policies regarding that, though.

[extra88]

Banks might accept such more-than-half bills as a courtesy to their customers but ultimately it's the US Treasury that will take them and redeem them. If you have a bunch of partially destroyed notes, you should go to them.

http://bep.gov/services/currencyredemption.html

https://www.npr.org/2017/07/07/535920428/the-office-where-mu...