Detailed answer — how Missouri law treats a co-tenant’s loan or refinance

First, identify how title is held. When heirs inherit real property in Missouri, they commonly hold title as tenants in common (each person owns an undivided fractional interest). Title could also show joint tenancy with right of survivorship if the prior owner created that form of ownership. The form of title affects what a co-tenant can do alone.

Can one co-tenant take a loan on the whole property without the others?

No. A single co-tenant generally cannot mortgage or refinance the entire property in a way that legally binds the other co-owners if those co-owners do not sign the loan documents. A lender typically requires signatures from all owners when it expects to mortgage the whole parcel. If a lender accepts only one co-tenant’s signature, the mortgage will, in most cases, attach only to that co-tenant’s undivided interest—not to the interests of the non-signing co-owners.

But can a co-tenant encumber their own undivided interest?

Yes. A co-tenant may sell or mortgage their own undivided interest without the consent of the other co-owners. If that happens, the lender can foreclose on that co-tenant’s interest. Foreclosure of an individual co-tenant’s interest often results in a court-ordered sale of that interest. Because the interest is an undivided share in the whole property, that foreclosure sale can lead to a purchaser owning the former co-tenant’s share, or in practice a forced sale (partition) of the entire property to satisfy the debt.

What practical risks does this create for the non-signing co-tenant?

• You may keep your fractional interest, but your ability to occupy or control the property could change if a third party acquires the foreclosed interest.
• If the lender forecloses on the encumbered share, a purchaser or the court may force a sale of the property (partition sale). A partition sale can end your ownership of the real estate—even if you did not sign the loan—because the sale proceeds are distributed according to ownership shares.
• You may be invited (or pressured) to buy out the encumbering co-tenant’s interest or to refinance the entire loan with all owners’ signatures to clear title.

Legal remedies and actions under Missouri law

Key legal options commonly used in Missouri include:

• Record review and quiet title inquiries: Confirm exactly what was recorded at the county recorder of deeds: deeds, mortgages, and releases. Public records determine who signed what and when.
• Challenge improper mortgage documents: If a co-tenant forged signatures, misrepresented ownership, or otherwise acted fraudulently, you can pursue an action to set aside the mortgage or sale and seek damages.
• Negotiation with the lender or co-tenant: Sometimes lenders will work with non-signing co-owners to restructure or cure a mortgage to avoid a costly foreclosure or partition sale.
• Partition action: Missouri law permits a co-owner to ask a court to partition the property (divide it physically if practicable or order sale and distribution of proceeds). A forced sale may be ordered in connection with foreclosure of an individual co-tenant’s interest. See Missouri statutes and procedures on partition actions through the Revisor of Statutes: https://revisor.mo.gov/ (search “partition”).
• Protective motions: In some cases you can seek injunctions to stop a foreclosure or sale while you challenge the encumbrance, especially where fraud or misrepresentation is alleged.

How foreclosure on a single co-tenant’s interest typically plays out

1. The co-tenant who took the loan uses their undivided interest as collateral.
2. If they default, the lender can foreclose on that undivided interest.
3. Foreclosure may transfer the debtor co-tenant’s share to the foreclosing party or lead to an order for partition sale of the property.
4. At a partition sale, proceeds are split according to ownership shares. Non-debtor co-owners receive proceeds for their share but may lose possession of the property itself.

Hypothetical example

Two siblings inherit a house in St. Louis as tenants in common (50% each). One sibling refinances and signs a mortgage using only their name. The lender records a mortgage against that sibling’s undivided 50% interest. Later the sibling defaults. The lender forecloses on that 50% interest. The foreclosure purchaser asks the court for a partition sale to sell the whole property; the court orders the sale and distributes proceeds 50/50. The other sibling receives monetary proceeds but no longer owns the house. This can happen even though the non-signing sibling never signed the loan.

Where to look in Missouri law

Missouri’s statutory code and court rules govern partition and foreclosure procedures. For official statutes and to research partition and foreclosure procedures, use the Revisor of Missouri’s statutes: https://revisor.mo.gov/ (search keywords such as “partition,” “foreclosure,” and “mortgage”).

Important: The exact remedies and outcomes depend on the deed language, the recorded instruments, any loan documents, and the facts (e.g., fraud, forged signatures, or lender negligence). Because outcomes turn on details, consult a Missouri attorney to evaluate recorded documents and recommend next steps.

Helpful Hints — Practical steps if a co-tenant refinances or borrows without your approval

• Check the recorder of deeds. Pull the deed and mortgage records at the county recorder where the property sits to see exactly what was recorded and when.
• Order a title report. A title company can reveal liens, mortgages, and who signed which documents.
• Talk to the lender. Ask whether the lender intended to secure the whole property or only an individual’s interest. Ask for payoff statements or copies of loan documents.
• Document communications. Keep written records of all conversations and copies of documents you request or receive.
• Consider negotiation first. If possible, negotiate a resolution (payoff, refinance with all owners, buyout, or release of lien) to avoid litigation and sale.
• Act early. If you suspect fraud or an improperly recorded mortgage, quick action (a motion to quiet title, lis pendens, or injunction) can protect your rights while the matter is resolved.
• Prepare for partition. If foreclosure seems likely, evaluate whether you want to buy out the other party’s interest or pursue partition yourself to control timing and method of sale.
• Consult a Missouri real estate attorney. A lawyer can analyze the title, the loan documents, and Missouri case law and statutes applicable to your situation.

For statutory text and procedures, review the Missouri Revised Statutes at the Revisor of Statutes: https://revisor.mo.gov/.