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Charles and Marcia are married cash-basis taxpayers. In 2012, they had interest income as follows:
• $500 interest on federal income tax refund.
• $600 interest on state income tax refund.
• $800 interest on federal government obligations.
• $1,000 interest on state government obligations.
What amount of interest income is taxable on Charles and Marcia’s 2012 joint income tax return?