A deed of sale does not automatically become completely invalid merely because one or more co-owners did not sign it. Under Philippine law, a co-owner may generally sell his or her own undivided share without the consent of the others. However, the buyer normally acquires only that seller’s share—not the entire property and not the shares belonging to the non-signing co-owners.

The result changes when the deed sells a specific physical portion, includes an unauthorized signature, excludes an heir from an estate settlement, involves conjugal or community property, or violates restrictions on foreign ownership. The wording of the deed, the source of the co-ownership, and the seller’s actual authority all matter.

The Basic Rule: A Co-Owner Can Sell Only What He or She Owns

Article 493 of the Civil Code provides that each co-owner has full ownership of his or her share and may sell, assign, or mortgage it. The effect of the transaction, however, is limited to the portion ultimately allotted to that co-owner when the property is partitioned. (Lawphil)

This produces two important rules:

A co-owner does not need the other co-owners’ permission to sell an undivided share.
A co-owner cannot transfer the shares of the other co-owners without their consent or valid authority.

An undivided share is an ideal or percentage interest in the whole property. For example, if four siblings own land in equal shares, each owns an undivided 25% interest throughout the property. Before partition, none of them automatically owns a particular corner, room, floor, or fenced section.

The Supreme Court has repeatedly held that when one co-owner purports to sell the entire co-owned property, the sale is generally effective only as to that seller’s share. The buyer takes the seller’s place and becomes a co-owner with the people who did not sign. This doctrine was reiterated in Heirs of Caburnay v. Heirs of Sison, G.R. No. 230934, December 2, 2020. (Supreme Court E-Library)

Simple example

A property is owned by Ana, Ben, Carla, and Dan, each with a 25% share.

Ana alone signs a deed stating that she is selling “the entire property” to Pedro.

Subject to other legal issues:

Pedro may acquire Ana’s 25% undivided share.
Pedro does not acquire Ben’s, Carla’s, or Dan’s shares.
Pedro becomes a co-owner with Ben, Carla, and Dan.
Pedro cannot automatically occupy a particular 25% portion unless the co-owners agree or the property is partitioned.

When All Co-Owners Must Sign

All co-owners should sign when the transaction is intended to transfer the entire property with complete ownership to the buyer.

Unanimous consent is also normally required when the deed attempts to sell a specific, physically identified portion before the property has been partitioned.

Selling a specific portion is different from selling an undivided share

In Spouses Rol v. Racho, G.R. No. 246096, January 13, 2021, the Supreme Court explained that a co-owner may sell an undivided aliquot share but cannot, without the others’ consent, select and sell a particular portion described by boundaries or “metes and bounds.” Allocating a definite portion effectively determines how the common property will be divided, which requires the participation of all co-owners. (Supreme Court E-Library)

Consider a one-hectare property owned equally by two sisters:

One sister may sell her undivided one-half interest.
She cannot unilaterally declare that the western 5,000 square meters belong to her and sell that exact area unless there has already been a valid partition or the other sister agrees.

In some cases, a court may examine whether the parties actually intended to transfer only the seller’s undivided interest. But a buyer should not rely on the possibility that a defective sale will later be judicially reinterpreted. Spouses Rol itself shows how an improper extrajudicial partition and sale can result in the cancellation of subdivisions and titles, even though some undivided interests may still be recognized. (Supreme Court E-Library)

A Notarized Deed Does Not Cure Missing Ownership or Consent

Notarization converts a properly acknowledged deed into a public document and is normally necessary for registration. Article 1358 of the Civil Code requires transactions transferring real rights over immovable property to appear in a public document. (Lawphil)

But notarization does not:

Give the seller ownership of another co-owner’s share.
Convert verbal permission into a valid written authority to sell land.
Validate a forged signature.
Cure the exclusion of a compulsory heir.
Make a prohibited sale to a foreigner valid.
Replace the written consent required from a spouse for community or conjugal property.

A notary verifies the execution and acknowledgment of the document. The notary does not adjudicate ownership. Even registration with the Registry of Deeds cannot transfer more rights than the seller legally possessed.

A buyer may therefore hold a notarized and even registered deed but still acquire only an undivided share—or face cancellation of the resulting title—if the seller lacked authority over the remaining shares.

What If One Co-Owner Claimed to Represent Everyone?

A co-owner may sign for another owner only if properly authorized.

Article 1874 of the Civil Code states that when land or an interest in land is sold through an agent, the agent’s authority must be in writing; otherwise, the sale is void. Article 1878 further requires a special power of attorney for a transaction transferring ownership of immovable property. (Lawphil)

A general statement such as “My siblings told me I could sell it” is unsafe and normally insufficient.

The Special Power of Attorney, or SPA, should clearly identify:

The principal or co-owner giving authority.
The authorized representative.
The property, preferably using the title number and technical description.
The authority to negotiate and sell.
The authority to agree on the price and terms.
The authority to sign and notarize the deed.
The authority to process BIR, assessor, treasury, and Registry of Deeds requirements.
The authority to receive payment, if intended.

Article 1317 also provides that a person cannot contract in another person’s name without authority. An unauthorized contract generally cannot bind the supposed principal unless properly ratified. (Lawphil)

Special Rules for Inherited Property

Inherited property is one of the most common sources of co-ownership disputes in the Philippines.

Under Article 1078 of the Civil Code, when there are two or more heirs, the decedent’s estate is owned in common by the heirs before partition, subject to the estate’s debts. (Lawphil)

This can be true even when:

The title remains in the deceased parent’s name.
One sibling possesses the owner’s duplicate title.
Only one heir has been paying real property taxes.
One heir has occupied or cultivated the property for many years.
The other heirs live abroad.
The tax declaration has been transferred to one person.

Possession of documents or payment of taxes does not, by itself, authorize one heir to sell everyone’s inheritance.

Can one heir sell a share before estate settlement?

An heir may generally sell his or her hereditary rights or undivided interest. The buyer then acquires that interest subject to estate settlement, payment of debts, determination of the heirs, and eventual partition.

However, the heir cannot safely sell a particular house, lot, or exact area as exclusively his or hers before that property has been validly adjudicated.

An extrajudicial settlement that completely excludes an heir who neither knew about nor consented to it may be declared fraudulent and void. In Spouses Rol v. Racho, the Court invalidated an extrajudicial settlement and the subdivisions created from it because a co-heir had been excluded. (Supreme Court E-Library)

Co-heirs may have a right of redemption

Under Article 1088, when an heir sells hereditary rights to a stranger before partition, the other co-heirs may take the buyer’s place by reimbursing the purchase price within one month from written notice of the sale. (Lawphil)

This right is separate from the general right of legal redemption available to co-owners under Articles 1620 and 1623. For ordinary co-ownership, the period is generally 30 days from written notice. The law also requires written notice before the deed may be recorded with the required vendor’s affidavit. (Lawphil)

Because these periods are short, a co-owner considering redemption should document the exact date and manner in which written notice was received.

Spouses Are Subject to Different Rules

Do not assume that the Article 493 rule always applies simply because a husband and wife appear to be “co-owners.”

If the property forms part of the absolute community of property or conjugal partnership of gains, Articles 96 and 124 of the Family Code apply. Disposition or encumbrance without the other spouse’s written consent or court authority is void, although the transaction may operate as a continuing offer that can be accepted before it is withdrawn. (Lawphil)

This is an important exception to the ordinary co-ownership rule. A spouse cannot necessarily sell a supposed “one-half share” in existing community or conjugal property as though the property had already been liquidated and divided.

Before accepting a deed signed by only one spouse, check:

When the property was acquired.
When the marriage took place.
The applicable marital property regime.
Whether the property is exclusive or part of the community or conjugal partnership.
Whether there is a prenuptial agreement.
Whether the marriage or property regime has already been dissolved and liquidated.
Whether the non-signing spouse gave written consent or a court issued authority.

What Foreign Buyers and Overseas Co-Owners Should Know

A foreigner generally cannot purchase Philippine land

Article XII, Section 7 of the Constitution generally prohibits the transfer of private land to persons or entities not qualified to acquire lands of the public domain, except through hereditary succession. A foreigner cannot avoid this restriction by purchasing an undivided co-ownership share in land. (Lawphil)

A foreigner may inherit Philippine land through hereditary succession. Condominium units may also be acquired within the limits imposed by the Condominium Act, including the restriction on excessive foreign interest in the condominium corporation or common areas. (Lawphil)

A co-owner abroad can sign through an SPA

A co-owner living overseas does not necessarily have to travel to the Philippines. The owner may execute an appropriately drafted SPA or, in some transactions, the deed itself abroad.

The BIR’s current documentary checklist recognizes a certification from the Philippine Consulate or an apostille when the deed of sale or SPA is executed abroad.

For practical processing:

Prepare the document in the form required for use in the Philippines.
Have it properly notarized under the law of the country where it is signed.
Obtain an apostille when the country uses the Apostille Convention process.
Where apostille treatment is unavailable or inapplicable, follow the authentication procedure required by the appropriate Philippine Embassy or Consulate.
Send the original authenticated or apostilled document to the Philippines when the BIR or Registry of Deeds requires the original.

Names, signatures, civil status, title numbers, and property descriptions must be consistent across the deed, SPA, passport, title, tax declaration, and BIR records. Small discrepancies frequently delay processing.

How to Check Whether the Deed Is Effective

1. Obtain a fresh certified copy of the title

Request a certified true copy from the Registry of Deeds rather than relying solely on a photocopy or the owner’s duplicate.

Check:

All registered owners.
Civil status.
Existing mortgages.
Adverse claims.
Notices of lis pendens.
Restrictions and annotations.
Whether the title has already been cancelled or replaced.
Whether the technical description matches the property being sold.

2. Identify the source of the co-ownership

Determine whether the property was:

Purchased jointly.
Inherited.
Donated to several people.
Acquired during marriage.
Awarded through an estate settlement.
Subdivided under a previous partition.
Registered under a condominium arrangement.

The source affects the applicable rules.

3. Compare the deed with the seller’s actual share

Look for language such as:

“Entire parcel.”
“All rights, interests and participation.”
“Undivided one-half share.”
“A portion containing 300 square meters.”
“Western portion.”
“Hereditary rights.”
“Rights and interests in the estate.”

A deed selling an undivided percentage is legally different from a deed selling a fixed physical section.

4. Verify every signature and authority

For each owner, confirm whether that person:

Personally signed.
Signed through a duly authorized attorney-in-fact.
Was already deceased on the signing date.
Was a minor or under guardianship.
Was married and required spousal participation.
Was a corporation requiring board authority.
Executed an overseas document that was properly apostilled or authenticated.

5. Trace the payment

Determine:

Who received the purchase price.
Whether payment was for the entire property or only one share.
Whether the non-signing owners received or accepted any part of the price.
Whether there was an express or implied ratification.
Whether receipts, bank transfers, or acknowledgments exist.

Acceptance of benefits may become relevant, but it should not be assumed to cure every defect.

Options for Fixing an Incomplete Deed of Sale

The appropriate solution depends on whether the parties still cooperate.

Situation	Possible practical solution
Some owners agree but did not sign	Execute a confirmatory or amended deed signed by all required owners
An owner is abroad	Execute a properly drafted, notarized, and apostilled or authenticated SPA
Only one undivided share was intended	Replace or amend the deed so the exact undivided interest is clearly stated
A specific portion was sold before partition	Complete a valid partition first, then execute a deed for the allotted portion
Inherited property remains unsettled	Settle the estate, identify all heirs, pay estate obligations, and register the adjudication or partition
Buyer wants complete ownership	Purchase the remaining shares through separate deeds or one consolidated deed
Non-signing owner rejects the transaction	Recognize that the deed cannot transfer that owner’s share; consider partition or court remedies
Seller promised the whole property but owned only a share	Buyer may pursue enforcement only as to the seller’s share or seek rescission, refund, damages, or other contractual relief

Article 494 allows any co-owner to demand partition, subject to valid restrictions on partition. Partition may be made by agreement or judicial proceedings. If an indivisible property cannot be allotted to one owner with payment to the others, it may ultimately be sold and the proceeds divided. (Lawphil)

What a Non-Signing Co-Owner Can Do

A non-signing co-owner should first determine whether the sale has merely been notarized or has already been registered.

Practical protective steps may include:

Obtain certified copies of the title, deed, SPA, tax declarations, and related registration records.
Send a written notice stating that no consent or authority was given.
Preserve proof of ownership, inheritance, possession, and communications.
Consider an affidavit of adverse claim when the legal requirements under Section 70 of Presidential Decree No. 1529 are present.
If a court action affecting title or possession is filed, consider registration of a notice of lis pendens under Section 76 of the same decree.
Seek an injunction when there is an immediate risk of another transfer, construction, demolition, or dispossession.
File the appropriate action for declaration of rights, nullity or unenforceability, reconveyance, cancellation of title, partition, accounting, possession, or damages, depending on the facts. (Lawphil)

Barangay conciliation may be a precondition before filing certain disputes when the parties fall within the Katarungang Pambarangay system. Section 412 of the Local Government Code generally requires prior confrontation before the lupon in covered cases, subject to statutory exceptions. (Lawphil)

Real actions are generally filed where the property is located. Whether the case belongs initially in a first-level court or the Regional Trial Court may depend on the assessed value and the relief requested under Batas Pambansa Blg. 129, as amended by Republic Act No. 11576. (Lawphil)

Documents Commonly Required to Register a Valid Sale

For an ordinary taxable transfer of titled real property, the documents commonly include:

Document	Purpose
Notarized deed of absolute sale	Evidence of the transfer
Certified true copy of the OCT, TCT, or CCT	Verification of registered ownership
Owner’s duplicate title	Presented for registration
Certified tax declaration for land and improvements	Valuation and local tax processing
TINs of sellers and buyers	BIR processing
Government-issued IDs	Identity verification
PSA marriage certificate, when applicable	Verification of civil status and spousal requirements
SPA	Authority of an attorney-in-fact
Apostille or consular certification	Overseas execution
Estate settlement documents	Required when an owner has died
BIR electronic Certificate Authorizing Registration	Proof of tax clearance for registration
Transfer tax receipt	Local government transfer requirement
Real property tax clearance	Confirmation of updated local taxes

The BIR’s checklist expressly requires a notarized deed, TIN information, certified tax declarations, certified title copies, applicable marriage records, authority documents, and apostille or consular certification for documents executed abroad.

Taxes, Fees, and Likely Processing Time

For real property classified as a capital asset, the sale commonly involves a 6% capital gains tax based on the higher applicable tax base, together with documentary stamp tax. Different rules may apply when the property is an ordinary asset, part of a business, subject to VAT or expanded withholding tax, or transferred through estate settlement. The capital gains tax return for an ordinary capital-asset sale is generally filed and paid within 30 days after the sale. (Bureau of Internal Revenue)

Other expenses may include:

Notarial fees.
Local transfer tax.
Registry of Deeds fees.
Certified-copy fees.
Survey and subdivision expenses.
Estate taxes and penalties, if inherited property remains unsettled.
Publication expenses for an extrajudicial settlement.
Professional and court fees for partition or title litigation.

A straightforward sale with complete documents may take several weeks to a few months from execution through BIR clearance, local transfer-tax payment, and issuance of a new title. Transactions involving deceased owners, missing heirs, overseas SPAs, subdivision surveys, title discrepancies, or tax deficiencies commonly take longer. A contested ownership or partition case may take years, especially if appealed.

Common Mistakes That Lead to Litigation

Relying on a tax declaration instead of the title

A tax declaration is relevant evidence and is needed for tax processing, but it does not automatically establish exclusive ownership against registered co-owners or heirs.

Buying a fenced portion from one co-owner

Physical possession or fencing does not necessarily mean that the seller exclusively owns that section. Before partition, a co-owner usually holds an undivided interest in the entire property.

Assuming the eldest child can sign for the family

The eldest child, family representative, administrator in practice, or person holding the title has no automatic authority to sell the shares of other heirs.

Excluding an heir who lives abroad

Distance, silence, or nonparticipation does not equal consent. An heir abroad remains entitled to the inherited share unless that right has been lawfully transferred, waived, adjudicated, or otherwise extinguished.

Paying the full price before verifying ownership

A buyer who pays for 100% of a property but receives only one co-owner’s share may have to sue for a refund or damages while remaining an involuntary co-owner with the seller’s relatives.

Treating registration as absolute protection

Registration gives notice and affects third parties, but it does not necessarily validate a transfer made by someone who did not own or have authority over the property sold. In Spouses Rol, titles and subdivisions produced by a defective estate settlement were invalidated. (Supreme Court E-Library)

Frequently Asked Questions

Is a deed of sale void if only one co-owner signed?

Not necessarily. It may be valid as a sale of the signing co-owner’s undivided share. It generally does not transfer the shares of the owners who did not sign.

Can one co-owner sell the entire property?

A co-owner may sign a deed purporting to sell the entire property, but the buyer ordinarily acquires only the seller’s share. Complete ownership requires the consent or valid representation of all owners, subject to special rules such as those governing marital property.

Can the buyer force the other co-owners to honor the sale?

The buyer normally cannot force non-signing co-owners to sell their shares merely because one owner promised the whole property. The buyer may, however, assert the acquired undivided share and seek partition.

Can a co-owner sell a particular portion of the land?

Generally, not before partition unless all co-owners consent. A co-owner may sell an undivided percentage but cannot unilaterally select the exact physical portion that will belong to the buyer. (Supreme Court E-Library)

Does notarization make an incomplete deed valid?

No. Notarization does not create ownership, supply missing consent, validate a forgery, or cure the absence of written authority.

What happens if one signature was forged?

A forged signature conveys no rights from the person whose signature was falsified. The affected owner may seek cancellation, reconveyance, and other civil relief. Forgery and the use of falsified documents may also create criminal liability depending on the evidence and circumstances.

Can an heir sell inherited land without the signatures of the other heirs?

The heir may generally sell his or her hereditary rights or undivided interest. The heir cannot transfer the other heirs’ interests or safely sell a particular estate property as exclusively owned before proper settlement and partition.

Can the other co-owners buy back the share sold to a stranger?

They may have a right of legal redemption under Article 1620, generally exercisable within 30 days from written notice under Article 1623. Co-heirs may instead fall under Article 1088 when hereditary rights are sold before partition. (Lawphil)

Can the missing co-owner sign later?

Yes, depending on the circumstances. The owner may execute a confirmatory deed, amended deed, ratification, or new deed. For land transactions through a representative, the required written authority must be properly documented.

What if the non-signing co-owner is already dead?

The deceased owner cannot be represented by another person merely through an old verbal arrangement. The estate must be addressed through the appropriate settlement proceedings, and the lawful heirs or court-appointed representative must act within their legal authority.

Key Takeaways

A deed of sale signed by only one co-owner is not automatically invalid in its entirety.
The signing co-owner may ordinarily transfer only his or her undivided share.
The buyer usually becomes a co-owner with the people who did not sign.
Selling a specific physical portion before partition generally requires the consent of all co-owners.
Notarization and registration do not cure lack of ownership, authority, or consent.
A person signing for another owner needs proper written authority, usually a Special Power of Attorney.
Inherited property requires careful identification of every heir and proper estate settlement.
Community or conjugal property is governed by stricter Family Code rules requiring the other spouse’s written consent or court authority.
Foreign buyers remain subject to constitutional land-ownership restrictions.
Written notice is crucial because legal-redemption periods may begin upon receipt of proper written notice.