Final answer:
For plan year 2024, the 2023 federal poverty level income numbers are used to calculate APTC eligibility.
Step-by-step explanation:
For plan year 2024 applications, the federal poverty level income numbers that will be used to calculate APTC eligibility come from the previous year, which would be 2023. This approach ensures that the most recent poverty level income data available at the time of application is used for determining eligibility for Advanced Premium Tax Credits (APTC).