Internal Revenue Code sections 401(a) and 501(a) set out requirements for qualification of employee benefit trusts and the tax-exempt status of these trusts. Form 5300 is used to request a determination letter from the IRS for the qualification of a defined benefit or a defined contribution plan and the exempt status of any related trust.
The latest form for Application for Determination for Employee Benefit Plan expires 2024-01-31 and can be found here.