There are three possible import contexts:
In both desktop and online versions, provide menu option to allow user to upload file or directly import their data.
Browse to the file. Replace 'TXF' with 'JSON, PDF, or TXF'.
Since many non-financial institutions issue tax documents, don't limit this this to "Financial Institutions".
At the beginning of the K-1 interview experience, prompt the user to upload or directly import their K-1 data.
Ask for the partnership EIN as the first interview item.
If this EIN is from a known partnership API relationship, prompt the user to electronically import their K-1 data.