As part of our commitment to improve and extend our API offerings, we will add some flexibility to our Income and Expenditure APIs.
We will change the behavior of the 'category' properties for these APIs and remove the enums from them. The APIs will from December 11th 2020 accept plain strings up to 255 characters.
We will publish allowed values on our Reference data page on our developer hub.
For reference usage please look at our transaction API which currently has this behavior.