Set tax to only charge on 28 days or less

In Palm Desert I don't have to charge tax for stays 29+ days. I don't see where I can set the tax setting to only charge for 28 days or less. What am I missing?
Thanks

When you're creating/editing the tax, add a booking criteria to it for Number of Nights. See screenshot.

That'll let you set the max number of nights for which the tax applies.

thanks Chris!