AR considers you a resident for tax purposes if you spend more than 6 months of the tax year in AR. So you must file as a resident of AR, and ALL your income for 2020 is taxable by AR, including your earnings from IL.
Section 14, https://codes.findlaw.com/ar/title-26-taxation/ar-code-sect-26-51-102.html
In the My Info section of TT, enter AR as your State of Residence, and indicate that you had other state income from IL. You must file a non-resident IL tax return (in addition to your resident AR return) if your IL earnings exceeded the IL personal exemption amount of $2,325.
In TurboTax, be sure to complete your non-resident IL return first, before your do your AR return. AR will credit you for the tax paid to IL on the portion of your income taxed by both states.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
