During 2022, Christiana's employer withheld $1,500 from her wages for state income taxes. She claimed the $1,500 as an itemized deduction on her 2022 federal income tax return which included $14,000 of itemized deductions (the 2022 standard deduction was $12,950). Christiana is single. On her 2022 state income tax return, her state income tax was $900. As a result, Christiana received a $600 refund in 2023. What amount must Christiana include in income in 2023?