Tenants in Common Brokerage Accounts

By Ryan O'Connell, CFA, FRM Published October 14, 2026

A tenants in common brokerage account lets co-owners hold separate shares of one investment portfolio, including unequal shares, without automatically leaving a deceased owner’s interest to the survivor. It can suit people who invest together but want different ownership percentages or different heirs. Before pooling assets, establish what each person owns, who can give instructions and how either owner will leave the arrangement.

What Is a Tenants in Common Brokerage Account?

Tenants in common, or TIC, describes an ownership registration. In the ordinary taxable brokerage account discussed here, each owner holds an undivided interest in the common portfolio. That is a fractional interest in the shared assets, rather than exclusive ownership of particular stocks. The interests can be equal or unequal: for example, documented 50/50 or 75/25 shares. TIC does not select the investments or determine whether borrowing is permitted.

Adult siblings, unmarried partners and spouses may consider this arrangement when their contributions or intended heirs differ. These are possible use cases, not an eligibility guarantee. State law, the legal character of the assets and the firm’s acceptance of the registration matter. The personal investing fundamentals guide provides broader context for choosing an investment account.

State defaults are not uniform. California Civil Code §686 generally treats interests created for several persons as interests in common, with exceptions including partnership, expressly declared joint interests and community property. Florida §689.15 addresses both real and personal property and generally creates TIC unless survivorship is expressly provided, except for entirety estates. These are state illustrations, not a rule for every account nationwide.^{[2] [3]}

Ownership Percentages and Transaction Authority

Separate three questions: Who owns the assets? Who can trade or withdraw them? Who is responsible for account obligations? A percentage answers the first question. Review the signed account agreement and applicable law to answer the others. FINRA Rule 2090 requires firms to know essential customer facts and the authority of people acting for customers; it does not prescribe a universal set of powers for every TIC holder.^[4]

A 25% ownership interest is not, by itself, a 25% withdrawal limit. Ask whether either owner can trade, withdraw cash, transfer securities or authorize borrowing independently. If both signatures are important, confirm whether the firm actually supports and records that requirement. A private promise between owners should not be assumed to change the instructions the firm is authorized to accept.

Document the initial interests, each contribution and the treatment of later deposits, withdrawals and expenses. New money might purchase additional ownership, preserve existing percentages or transfer value to the other owner. Establish the legal treatment before funding and confirm the firm’s accepted process for recording changes. A displayed percentage or a deposit total is not a substitute for effective ownership records.

Eligibility, Permissions and Costs

Confirm that the firm offers TIC for the intended owners and jurisdiction. Ask about its identity, legal-capacity, residence, tax-documentation and account-minimum requirements. Do not infer acceptance from a generic “joint account” option. The accepted registration should identify the intended ownership form, and each owner should understand the documents they sign.

Choose cash or margin permissions separately from ownership. A cash account requires full payment for purchased securities. An approved margin account permits borrowing; borrowing adds interest expense and can expose the owners to forced sales and losses exceeding the funds deposited. Trading permissions and available products also need separate confirmation. FINRA explains these distinctions and the role of account agreements.^[5] Compare them with the margin trading guide before adding leverage to shared ownership.

Compare the actual fee schedule and disclosures: transaction commissions, ongoing account or advisory fees, transfer and withdrawal charges, and any other services you intend to use. For funds, examine the expense ratio as well as trading costs. Ask how expenses will be allocated between owners. A TIC label does not establish a special fee discount or a single nationwide cost schedule.

Taxes: Follow the Legally Established Interests

TIC does not turn a taxable account into an IRA, make ordinary deposits deductible or defer tax on investment income. Interest, dividends and realized gains keep their usual tax character. Ordinary taxable funding is not governed by an IRA contribution ceiling; compare the separate tax-wrapper rules in the retirement account planning guide.

IRS Publication 550 says that each owner’s share of interest and dividends from jointly held property is determined by local law. It is not automatically half, nor can a privately chosen percentage override the property’s actual legal character. For a sale, use the interests and adjusted tax-lot basis applicable to the securities sold; gain or loss depends on the amount realized relative to adjusted basis.^{[6] [7]}

Tax Forms Do Not Establish Beneficial Ownership

A joint account containing combined funds may report income under the first-listed owner’s taxpayer identification number. That does not make all the reported income legally theirs. Publication 550 describes nominee reporting when interest or dividends reported to one person belong to another, including Schedule B adjustments and applicable Forms 1099-INT or 1099-DIV for the actual owner and the IRS. It provides a spouse exception to those nominee-form filing requirements.^[6]

Reconcile the tax forms to legal ownership and retain each income category. Use the applicable year’s reporting instructions rather than copying an older publication’s filing dates. The tax-aware portfolio management guide covers portfolio tax decisions beyond these ownership-allocation questions.

Unequal Funding Can Raise Gift and Basis Questions

If one person supplies assets but transfers an ownership interest to another for less than full value, gift-tax rules may apply. Unequal deposits alone do not establish whether or when a completed gift occurs; analyze the rights actually transferred. The donor is generally responsible for gift tax, and a Form 709 filing requirement does not necessarily mean immediate tax is payable.^{[8] [9]}

Gifted securities have their own basis rules. Do not replace their historical basis with current market value simply because a new owner joins the account. Preserve purchase records and obtain tax advice before changing ownership.^[13] The personal tax strategy guide offers broader planning context; the legal and tax treatment of a particular transfer still needs its own analysis.

Funding, Withdrawals and Transfers

Before sending bank cash or transferring securities, confirm accepted funding sources, title requirements, the destination registration and authorized instructions. Keep evidence of who supplied each asset and its basis. Ask how deposits become available for trading and withdrawal; deposit holds, trade settlement and withdrawal processing are different issues. The firm should explain its actual requirements rather than leaving the owners to infer them from another account type.

For a withdrawal, distinguish moving cash already in the account from selling investments to raise cash. A sale can realize taxable gain or loss even if its proceeds remain invested; withdrawing the resulting cash is a separate step. For an exit, agree which assets or cash will be distributed, who bears any expenses, and whether the distribution changes ownership rights.

Ask both firms whether an in-kind securities transfer is possible, which assets they can carry and what authorization is needed. Keeping the same beneficial owners differs from adding or removing an owner. FINRA Rule 11870 permits transfer exceptions for mismatched account titles or types and missing or improper authorization. Nontransferable holdings also need separate instructions. An individual-to-TIC transfer should not be assumed to work as an ordinary matching-title account transfer.^[14]

Changing percentages is likewise a transfer-of-rights question, not just an account-setting change. Confirm the legal documentation, tax consequences and firm’s accepted registration process before a buyout or revised funding arrangement. Do not assume that an in-kind transfer, ownership change or new deposit is automatically tax-free.

What Happens When a TIC Owner Dies?

The survivor keeps their existing interest. The deceased owner’s share follows an effective estate disposition or applicable intestacy law, rather than passing automatically to the co-owner through TIC. California Probate Code §7000, subject to §7001, illustrates passage to the will’s devisee or intestate heirs subject to administration. Entitlement to inherit is distinct from authority to operate the brokerage account.^{[1] [10]}

Probate may be needed, but full court probate is not inevitable in every case. California Courts describes a conditional small-estate procedure for personal property, including stocks. The applicable value limits, eligibility, documentation and timing need current verification; this is not a recommendation that any particular estate qualifies. Coordinate the TIC share with your wills and estate plan.^[11]

Notify the firm promptly and obtain its estate-processing instructions. FINRA explains that documents and authority checks differ by account and firm; a death certificate, evidence of the representative’s appointment or other documents may be needed. A new estate or heir account may be part of the transfer. Ask about restrictions affecting the deceased interest and the survivor’s access while the review is pending. No fixed access period or automatic liquidation should be assumed.^[12]

Do not assume a TIC registration includes a transfer-on-death beneficiary option. If you want a beneficiary designation, establish whether the governing law and firm permit a valid arrangement for this registration and what it will actually transfer. TIC alone creates neither that designation nor survivorship rights.

Inherited Basis Applies to the Interest Inherited

IRS Publication 551 generally assigns inherited property a basis equal to its date-of-death fair market value, subject to valuation rules and exceptions. The adjustment can be downward as well as upward. In an ordinary separate-property TIC arrangement, the survivor’s previously owned share is not inherited merely because the co-owner dies.^[13]

Spouses must also determine whether the assets are separate or community property. Publication 551 describes a different community-property rule that can adjust both spouses’ halves when its conditions are met, including at least half the property’s value being includible in the decedent’s gross estate. Do not infer that treatment from a TIC account label alone.^[13]

Comparison: TIC Versus Other Ownership Arrangements

Survivorship and separate estate shares answer different inheritance goals. The IRS legal summary distinguishes those arrangements, while the estate-planning guide provides broader context for coordinating ownership and intended heirs.^[1]

For spouses, compare the property’s legal character and applicable marital rights before selecting a title. The personal tax planning guide provides broader tax context. For trustee-managed succession, consider whether a properly established and funded revocable trust serves the intended plan, with counsel’s help. The wills and trusts guide introduces that alternative; merely renaming a TIC account does not establish or fund a trust.

How to Evaluate a TIC Account Before Opening It

1. Establish the legal interests. Agree on percentages, contribution sources, expenses, withdrawals and heirs. Resolve separate-versus-community-property questions with qualified counsel when relevant.
2. Confirm availability and registration. Ask whether the firm accepts TIC for the proposed owners and jurisdiction. Request the intended registration expressly and retain its accepted records.
3. Check authority and obligations. Read what each holder can do, whether dual approval is supported, what liability provisions apply and how disagreements are handled. Confirm any delegated authority separately.
4. Select permissions and compare costs. Choose cash or approved margin and the investment permissions actually needed. The investment account fundamentals guide provides context for fully paid investing. Review fees, fund expenses and risks before funding.
5. Complete identity and tax documentation. Obtain the firm’s requirements for every owner and authorized person. Confirm whose taxpayer identification number will be used and how ownership records will support tax reporting.
6. Fund and plan for changes. Verify bank or securities-transfer instructions, accepted assets and holds. Keep contribution and basis records, and establish a process for exits, incapacity and death.

Common Mistakes

• Treating percentages as access controls. Check actual authority and supported approval arrangements independently of economic shares.
• Assuming deposits automatically reset interests. Determine the legal treatment and firm’s documentation process first.
• Splitting every tax form equally. Reconcile ownership, income character, tax-lot basis and nominee reporting.
• Expecting automatic survivor inheritance. Coordinate each interest with an effective estate plan and applicable law.
• Resetting the entire portfolio’s basis at death. Identify the inherited interest and any special property-character rules.
• Adding an owner merely for assistance. Ownership can create gift, dispute and inheritance consequences. Consider whether properly documented authority would better address the need.

Risks and Limitations

TIC combines investment decisions with ownership and recordkeeping responsibilities. Conflicting risk preferences, liquidity needs or heirs can make a shared portfolio difficult to manage. The registration does not prevent investment losses or establish blanket protection from creditors. Agree on how to handle disagreements and exits before investing, and obtain advice for the governing jurisdiction.

It also does not replace an incapacity plan. An owner’s inability to act raises different questions from death and inheritance. FINRA’s power-of-attorney guidance distinguishes the scope and durability of an agent’s authority and emphasizes state-law and firm-validation requirements. Discuss those arrangements separately from co-ownership.^[17]

Sources and Rule Dates

Research updated October 13, 2026. Tax explanations use Publication 550 (2025), Publication 551 (December 2025) and 2025 Form 709 instructions for continuing conceptual rules; no year-specific tax thresholds or filing deadlines are stated. California code passages and SIPC pages use saved official evidence from October 6, 2026. State illustrations and simplified estate procedures require a current check for the reader’s jurisdiction and facts.

1. IRS Internal Revenue Manual 5.17.3.9.1.3, Tenancy in Common (subsection dated January 7, 2011; personal-property and survivorship discussion).
2. California Civil Code §686 (ownership defaults and exceptions).
3. 2026 Florida Statutes §689.15 (survivorship and TIC).
4. FINRA Rule 2090 (customer facts and authority).
5. FINRA Brokerage Accounts (agreements, costs, cash and margin).
6. IRS Publication 550 (2025) (Joint accounts, TIN for joint account and nominee reporting).
7. IRS Topic 409, Capital Gains and Losses (sale proceeds and adjusted basis).
8. IRS Gift Tax FAQ (transfers for less than full consideration).
9. IRS Form 709 Instructions (2025) (Who Must File; filing versus tax due).
10. California Probate Code §7000 (subject to §7001; passage of property).
11. California Courts Small Estate Affidavit Guide (conditional personal-property procedure; verify current limits).
12. FINRA When a Brokerage Account Holder Dies (documents, legal authority and firm procedures).
13. IRS Publication 551 (December 2025) (gifted and inherited property; community property).
14. FINRA Rule 11870 (nontransferable assets and §(d)(3)(I)–(K) transfer exceptions).
15. SIPC Investors with Multiple Accounts (separate capacities and joint-account example).
16. SIPC What SIPC Protects (qualifying missing assets; market losses excluded).
17. FINRA Power of Attorney and Your Investments (March 2016; scope, durability and state law).