Viola $(45)$ is single. Her $2021$ federal itemized deductions totaled $$15,400,$ of which she claimed $$1,000$ of state income taxes paid in $2021.$ She filed her tax return on April $14,2022,$ and on May $1,2022,$ she received a $$1,000$ state income tax refund. How much of her $2021$ state income tax refund is taxable on her $2022$ federal return?