My spouse and I legally separated last September (2019). We are filing married separate, do I HAVE to give him my SS#?
But that is ALL I have to give him, correct? Name, SS#?
Yes that is correct. Unless you live in a community property state, then it gets more complex.
See this TurboTax website for filing separately in a community property state - https://ttlc.intuit.com/community/married/help/married-filing-separately-in-community-property-state...