A self-directed IRA can invest in a wide array of assets. The IRS does not publish a list of approved investments. Instead, the tax code identifies a short list of prohibited assets. Anything not on that list is allowed, provided you follow the rules against self-dealing and transactions with disqualified persons.
The range is broad. Common asset classes held in self-directed plans include real estate (residential, commercial, raw land, rentals, flips), private loans and trust deeds, private company stock, cryptocurrency, tax liens and deeds, private equity and investment funds, and mineral rights. Conventional assets (stocks, bonds, and mutual funds) are permitted as well.
Two asset categories are specifically off-limits for IRAs under the tax code.
Life insurance contracts of any kind are prohibited under IRC Section 408(a)(3). This applies to all IRA types. A Solo 401(k) may hold life insurance in limited circumstances, but the rules are complex and the practical benefit is rarely clear.
Collectibles are prohibited under IRC Section 408(m)(2) for both IRAs and Solo 401(k)s. The list includes artwork, rugs, antiques, stamps, alcoholic beverages, gems, and most coins. There is a narrow exception for certain precious metals - specifically US Eagle coins and bullion meeting a 99.9% purity standard - but these must be held in the physical possession of the IRA custodian and cannot be titled to an IRA LLC or IRA Trust.
An IRA cannot hold shares of a subchapter S corporation. This is not an IRA rule. Rather this restriction stems from S corporation shareholder eligibility rules under IRC Section 1361, which limit ownership to individuals and certain trusts. A Solo 401(k), as a qualified retirement plan, is permitted to be an S corporation shareholder under IRC Section 1361(c)(6).
This information is provided for educational purposes only and should not be interpreted as tax, legal, or investment advice. Readers are encouraged to consult a qualified professional who can offer guidance based on their personal situation.