Small Business Payment for Performance Act of 2019 This bill allows a small business performing a construction contract awarded by a federal agency to request an equitable adjustment if the agency's contracting officer directs a change in the contract's performance without the agreement of the small business. The agency must provide the small business with an interim partial payment to cover additional costs resulting from such a change, and the small business must pay a first tier subcontractor or supplier the portion of the partial payment that is attributable to additional costs incurred due to the change.