In what state was your husband stationed in 2024, prior to his retirement? If he was stationed outside California, then his California tax status for 2024 would be non-resident, and he would be subject to CA income tax only if he had California-source income during that time. See Stationed outside California in Section D on page 5 of this CA tax publication:
https://www.ftb.ca.gov/forms/2023/2023-1032-publication.pdf
Some examples of "California-source" income would be income from a civilian job in California, or rental income from a property located in California. His military pay is not California-sourced.
If his main, primary home after his retirement date was Idaho, then for 2024 tax purposes he would be considered a part-year resident of ID. In that case all his income after his retirement date would be taxable by ID, unless specifically excluded by Idaho law. Idaho does allow limited deductions for military retirement pay if you meet certain conditions. You'll find the details here:
https://tax.idaho.gov/taxes/income-tax/individual-income/popular-credits-and-deductions/idaho-retire...
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
