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Can I upgrade?"
No, there is no upgrade path from TurboTax Home & Business to TurboTax Business. They are entirely separate products and mutually exclusive in the sense that TurboTax Home & Business cannot be used to prepare income tax returns for entities (e.g., a 1041 for an estate) while TurboTax Business cannot be used to prepare individual income tax returns (e.g., a 1040). In short, you need both products.