New Invoice: Getting Please configure tax for the selected contact

I 'm trying to create a new invoice for a client that I have previously invoiced many times before without an issue, but now getting the following message when attempting to save a Draft invoice for review:

Please configure tax for the selected contact

This has not been a requirement before. Has something changed?

I've attempted to configure the tax, but I'm not sure what to enter in the dialog. My work for this client is professional services which are not taxable in California.

Please help. Thanks.