We are also facing the same issue.
We are an Indian company registered in india.
We need the following documents from Upwork for Tax Compliance Purpose.
1. India PAN if available else "No Permanent Establishment" Declaration (Format is attached)
2. Tax residency Certificate
3. Declaration in Form 10F (Format is attached)
4. Tax Identification Number (TIN) in the country of residence. Where TIN is not available, a unique identification number.