I'm creating a new Tax Rate but do not see any drop down lists for the Tax Type and the Report Tax Type?

The Tax Type values are different for each Xero Organisation region, and include some values that can be updated and other (system values) that cannot be updated. You can get the full list of Tax Types here:

https://developer.xero.com/documentation/api/types#TaxTypes

Report Tax Types are also region specific and include a mix of values which can be used when creating and updating Tax Rates and others which are used for system tax rates and only returned on GET requests. You can get the full list of Region Tax Types here:

https://developer.xero.com/documentation/api/types#ReportTaxTypes

You can use these values to create your own custom drop down lists specific to your Xero organisation’s region.