We collect tax IDs as part of our Know Your Customer/Anti-money laundering policy. We use this to verify your identity your identity if you're applying for an individual account. We still collect it if you work for a company on Bitwage, even though you do not go through the verification process.
Bitwage will not proactively share your information with any government agency. with the exception of the IRS when certain thresholds are met for American users.