Can One Co-Owner Sell Their Share, and What Are the Limits?

Co-ownership (also called “undivided ownership”) exists when two or more persons own the same property or right in ideal or undivided shares, with no specific physical portion belonging exclusively to any one of them until partition. The governing rules are primarily found in the Civil Code of the Philippines (on co-ownership), plus related provisions on obligations, contracts, and property transfers. This article focuses on the practical and legal consequences of a co-owner’s attempt to sell or otherwise dispose of their “share,” and the limits imposed by law and by the nature of co-ownership.

1) What Exactly Does a Co-Owner Own?

A co-owner owns an ideal or aliquot share—a proportional interest in the whole property, not a carved-out room, lot corner, or floor. For example, if A and B co-own a parcel of land 50–50, each owns half of the entire land, not the “left half” or “right half” unless the property has been partitioned.

Key consequences:

A co-owner has the right to use and enjoy the property consistent with the rights of the other co-owners.
A co-owner may dispose of (sell, donate, assign, mortgage) only their ideal share, not a specific portion, unless partition has occurred.

2) Can a Co-Owner Sell Their Share?

Yes—Generally, a co-owner may sell their undivided share.

A co-owner may transfer their ideal share to another person, and the buyer simply steps into the seller’s shoes as a new co-owner with the same rights and burdens.

What the buyer receives:

An undivided interest in the property, proportionate to the share purchased.
The right to participate in management, share in benefits, and demand partition.
The obligation to respect the rights of the other co-owners and contribute to expenses.

What the buyer does not automatically receive:

Exclusive ownership of any specific physical portion of the property.
Unilateral control over the whole property.
A guaranteed “particular area” unless partition later assigns it.

3) The Fundamental Limit: A Co-Owner Cannot Sell Specific Portions as If Exclusively Owned (Absent Partition)

A frequent mistake is when one co-owner sells “the front part,” “the second floor,” or “a 100 sq.m. portion” of co-owned land without partition. In co-ownership, that specific part is not yet exclusively owned by anyone.

Legal effect:

The co-owner may validly sell only their ideal share.
If the deed purports to sell a definite physical portion, it is not automatically void in every situation, but it cannot prejudice the other co-owners’ rights and it is effective only to the extent of the seller’s share, subject to partition outcomes.
The buyer assumes the risk that the portion described may not be allocated to the seller when partition happens.

Practical implication:

Even with a notarized deed describing a definite area, the buyer may end up co-owning the whole property with others and may need to pursue partition to obtain a determinate portion—without certainty that it will match what was described.

4) Sale of Share vs. Sale of Entire Property

A co-owner cannot sell the entire property without authority from the others.

A co-owner acting alone cannot validly dispose of the entire property as if sole owner. If a co-owner “sells the whole land” without the consent of others:

The sale is valid only as to the seller’s ideal share.
As to the other co-owners’ shares, it is ineffective unless ratified or otherwise authorized.

A buyer who thought they purchased 100% may find themselves owning only the fraction corresponding to the seller’s share.

5) Co-Ownership Management: Acts of Administration vs. Acts of Ownership (Disposition)

Understanding what requires consent is crucial.

Acts of administration (generally majority rule)

Administrative decisions (e.g., ordinary repairs, routine management, leasing for reasonable terms in many contexts) are typically governed by majority interest (by share, not headcount), provided the decision does not alter the substance of ownership and does not prejudice others.

Acts of ownership or disposition (generally unanimity for common property; freedom for one’s own share)

Disposition of the common property as a whole generally requires consent of all co-owners (or proper authority).
Disposition of a co-owner’s own undivided share may be done by that co-owner alone.

6) The Special Limit That Matters Most in Practice: Legal Redemption by Co-Owners

When a co-owner sells their undivided share to a third person (someone who is not already a co-owner), the law grants the remaining co-owners a right of legal redemption—a statutory right to step in and purchase the share from the buyer under the same terms, within a limited period.

When legal redemption applies

The property is co-owned.
A co-owner sells their undivided share.
The buyer is a third person (not a co-owner).

When it does not typically apply

Transfer to an existing co-owner (because the buyer is not a “third person”).
Partition has already terminated the co-ownership (the property is no longer held in undivided shares).
Certain transfers that are not sales (depending on the transaction form and substance—though courts look at substance over form).

Time period

The redemption must be exercised within 30 days from written notice of the sale given by the seller (or buyer) to the other co-owners.

Important:

The 30-day period is triggered by written notice.
Without proper written notice, the redemption period generally does not run in the intended way, and disputes often center on whether notice was sufficient and when the period began.

If multiple co-owners want to redeem

Those who redeem do so in proportion to their existing shares, unless they agree otherwise.

How redemption works

The redeeming co-owner must reimburse the buyer for:

The purchase price stated in the deed; and
In proper cases, necessary expenses and costs tied to the sale (as recognized under redemption principles).

This legal redemption exists to prevent undesirable strangers from being forced into a co-ownership and to preserve stability in shared property arrangements.

7) What If the Co-Owner Sells Their Share Secretly?

A sale without informing other co-owners is still generally valid as a sale of the seller’s share. However:

The buyer takes the share subject to the co-owners’ right of legal redemption.
Litigation often arises over the sufficiency of notice, the actual sale price (including simulated price issues), and good faith.

A buyer purchasing an undivided share without securing waivers from other co-owners accepts the risk that the share may be redeemed.

8) What If the Co-Owner Sells Their Share to a Spouse, Child, or Relative?

If the buyer is not already a co-owner, they are typically still a “third person,” even if related to the seller. Relationship alone does not automatically remove legal redemption. What matters is whether the buyer is outside the co-ownership at the time of sale.

9) Can a Co-Owner Mortgage or Encumber Their Share?

Yes, a co-owner may mortgage their undivided share.

A co-owner can use their ideal share as collateral. The mortgage attaches to that undivided interest.

Limits and risk:

The mortgagee (lender) does not gain exclusive rights over any physical portion.
Upon partition, the encumbrance typically follows the portion adjudicated to the mortgagor to the extent consistent with the partition outcome.
If the mortgagor’s share is insufficient or complicated by partition or redemption, enforcement may be difficult in practice.

10) Can a Co-Owner Lease Out the Property?

This depends on scope and consent.

Lease of the entire property

Leasing the entire property generally requires authority consistent with co-ownership rules on administration. Longer-term leases can be treated as acts that significantly affect ownership interests, potentially requiring broader consent.

Lease of a specific portion

A co-owner cannot unilaterally lease a definite portion as if exclusively theirs, unless there is a prior agreement among co-owners or a de facto arrangement tolerated by them.

Effects in practice

Philippine property disputes often involve “informal partition” by tolerance—e.g., each co-owner occupies a specific area for years. Even then, this does not necessarily equal a formal partition that binds third parties, unless proper legal partition and registration occur where required.

11) Improvements, Repairs, and Expenses: How They Affect Sale of a Share

A buyer of an undivided share inherits not only rights but also financial responsibilities and may also inherit disputes.

Necessary expenses (preservation)

Co-owners must generally contribute proportionately to necessary expenses for preservation (e.g., real property tax, essential repairs).

Useful and luxury expenses

Reimbursement rules vary by necessity and benefit. A co-owner who spends for improvements without consent may face limits on reimbursement, and may have rights related to partition accounting.

Why this matters for sale

When a share is sold, there may be:

Unpaid taxes or expenses that affect the entire property.
Claims for reimbursements between co-owners.
Pending disputes that reduce value.

A buyer should investigate not only title but also the internal accounting and possession arrangements.

12) The Right to Demand Partition: The Ultimate Exit Mechanism

Co-ownership is generally considered a temporary or at least disfavored arrangement because it invites conflict. The law therefore recognizes the right of any co-owner to demand partition at any time, subject to limited exceptions.

Forms of partition

Voluntary (extrajudicial) partition – by agreement, often documented and, for registrable real property, registered.
Judicial partition – court-supervised division when co-owners cannot agree.

Limits on demanding partition

Partition may be restricted when:

There is a valid agreement to keep the property undivided for a limited period (within legal bounds);
The property is essentially indivisible, in which case it may be sold and proceeds divided; or
Partition would render the property unserviceable for its intended use, depending on context.

Relevance to sale of a share

A buyer of an undivided share may demand partition, but:

Partition can be costly, time-consuming, and contentious.
Physical division is not always feasible; the remedy may become sale of the whole and division of proceeds.
If the property is family land with strong opposition, practical enjoyment may be limited.

13) Co-Ownership by Inheritance: Common Real-World Scenario

Many co-ownerships arise when heirs inherit property before it is partitioned. Each heir becomes a co-owner of the estate property (or specific assets) in undivided shares, until partition or settlement.

Special practical issues in inherited co-ownership

Estate settlement requirements and tax issues can complicate transfers.
Titles may still be in the decedent’s name, affecting registrability.
One heir’s sale of hereditary rights or shares may be valid, but the buyer’s ability to register and enjoy the property may depend on settlement and partition.

14) Registration and Title Issues: Why “Valid Sale” May Still Be Hard to Enforce

For real property, enforceability against third persons and ease of asserting rights often depends on:

Whether the property is titled (Torrens system) or untitled;
Whether the transfer is registrable and actually registered; and
Whether the deed correctly identifies what is being conveyed (an undivided share).

Common pitfalls

Deed describes a definite portion rather than an undivided share.
Title remains in a prior owner’s name (e.g., deceased parent), blocking clean transfer.
Annotations and encumbrances exist.
The buyer assumes they can fence off an area immediately—leading to conflict, injunctions, and criminal complaints (e.g., trespass) depending on facts.

15) What Buyers of an Undivided Share Should Understand

Buying an undivided share is not like buying a normal lot.

The buyer must expect:

Co-ownership relationship with strangers or relatives.
Possible legal redemption by other co-owners.
Need for partition to obtain exclusive ownership of a definite portion.
Possible disputes over possession, boundaries, improvements, taxes, and income.

Strong practical safeguards:

Require proof of co-ownership shares and authority.
Obtain written acknowledgments or waivers from other co-owners when possible.
Clarify whether there is an existing informal allocation of use.
Confirm tax status, occupancy, and pending cases.

16) What Selling Co-Owners Should Understand

Selling one’s undivided share is lawful, but it carries duties and risks.

Key points for the selling co-owner:

Sell only what you own: your ideal share.
Provide proper written notice to co-owners if selling to a third party, because redemption issues can unravel the deal.
Avoid describing a specific portion as if exclusively owned unless a proper partition supports it.
If there are co-owner agreements on administration or use, disclose them to avoid liability for misrepresentation.

17) Remedies and Disputes: Typical Scenarios

(A) Other co-owners object to the entry of a buyer

They may:

Exercise legal redemption (if available and timely);
Demand partition;
Seek injunction if the buyer attempts exclusive possession beyond the purchased share.

(B) Buyer insists on occupying a specific portion immediately

Other co-owners may:

Resist and seek court relief, especially where the buyer’s act excludes them or alters the property.
Argue that no one can appropriate a definite part without partition.

(C) Seller sold “a specific portion”

Likely outcomes include:

The buyer may be treated as having bought an undivided share only.
The buyer may pursue partition to try to obtain that portion, with no guarantee.

(D) Disagreement on income from property (rent, harvest, etc.)

Co-owners generally share benefits proportionally, subject to agreements and accounting.

18) Summary of Core Rules (Philippine Context)

A co-owner may sell their undivided share without the consent of other co-owners.
A co-owner cannot sell a specific physical portion as exclusively theirs unless partition has determined it.
A sale by one co-owner of the entire property binds only their share unless others authorized or ratified it.
When a co-owner sells to a third person, the remaining co-owners generally have legal redemption, exercisable within 30 days from written notice of the sale.
The buyer becomes a co-owner and may demand partition, but must accept the realities and burdens of co-ownership.
Registration, estate settlement, and the exact wording of deeds can determine whether a “sale” is practically usable or becomes a dispute.

19) Practical “Limits” Checklist

A co-owner’s power to sell is real—but bounded by these limits:

Limit of object: only the ideal share can be freely sold.
Limit of effect: the sale cannot prejudice other co-owners’ shares.
Limit of possession: no unilateral exclusive possession of a definite portion without partition or agreement.
Limit of third-party entry: co-owners may redeem the sold share when sold to a third person.
Limit of enforceability: title/registration, estate status, and encumbrances may prevent clean enjoyment.
Limit of future outcome: partition may allocate different physical portions than expected.

20) Concluding Legal Position

In Philippine law, a co-owner generally has the freedom to sell their undivided share, but this freedom is constrained by the basic nature of co-ownership: no co-owner owns a specific part until partition. The most significant statutory check on selling to outsiders is legal redemption, which protects the remaining co-owners from being forced into co-ownership with a stranger. Because co-ownership disputes are often driven by possession and partition, the real-world limits are as much practical as they are legal: selling an undivided share is easy on paper, but turning that share into peaceful, exclusive ownership often requires agreement or formal partition.