Quick answer

Generally, yes. A co-owner may sell, assign, or mortgage only their undivided share in co-owned property without obtaining the other co-owners’ consent. The buyer steps into the seller’s position as a co-owner; the buyer does not automatically acquire exclusive ownership of any particular room, floor, or marked portion of the land.

A co-owner ordinarily cannot, without everyone’s consent or a valid partition, sell:

the shares belonging to the other co-owners;
the entire property as though solely owned; or
a specific physical portion identified by boundaries.

Even when a deed describes the whole property or a specific area, Philippine courts may recognize the transaction only to the extent of the seller’s actual undivided interest, subject to the outcome of partition. The exact effect depends on the deed, title, source of ownership, marital-property regime, prior partition, registration, and possible fraud or forgery.

The remaining co-owners may also have a 30-day right of legal redemption when an undivided share is sold to a third person. That period generally runs from legally sufficient written notice of the completed sale—not merely from rumors or informal knowledge.

What an “undivided share” means

In a co-ownership, each person owns a proportionate or ideal share in the property as a whole. Before partition, a one-half owner does not necessarily own the left half, ground floor, front portion, or any other fixed area.

For example, Ana and Ben each own an undivided one-half share in a 600-square-meter lot. Ben may sell his undivided one-half interest without Ana’s consent. The buyer generally becomes Ana’s co-owner of the entire lot. The buyer does not automatically become the exclusive owner of a particular 300-square-meter section unless that section was validly assigned through partition or all necessary co-owners consented.

This follows Article 493 of the Civil Code of the Philippines, which allows each co-owner to dispose of their part but limits the disposition, as against the other co-owners, to what may eventually be allotted to the seller when the co-ownership ends.

When consent is not required

Consent from the other co-owners is generally unnecessary when all of the following are true:

The seller is genuinely a co-owner.
The seller disposes only of their undivided interest.
The deed does not purport to bind the other owners or transfer their shares.
No separate legal rule requires consent, such as a rule governing community or conjugal property.
The seller’s authority and ownership documents are authentic.

The Supreme Court has repeatedly held that a buyer of an undivided share takes the seller’s place as co-owner. See, for example, Delos Santos v. Register of Deeds of Tarlac, G.R. No. 246096, January 27, 2021, and Heirs of Apolinario Reyes v. Garilao, G.R. No. 238468, July 6, 2022.

The other co-owners do not have a general right to block a lawful sale merely because they dislike the buyer. Nor does Article 1620 create a general right to force the selling co-owner to offer the share to them first. The statutory remedy ordinarily arises after a sale to a third person, through legal redemption.

When the sale exceeds the seller’s rights

Sale of the entire co-owned property

One co-owner cannot transfer ownership of the shares belonging to non-consenting co-owners.

However, describing such a transaction simply as “completely void” may be inaccurate. Supreme Court decisions generally recognize the sale, where legally possible, to the extent of the seller’s own undivided share. The buyer may become a co-owner rather than the sole owner promised in the deed. The non-consenting owners retain their shares.

This rule does not protect forged documents or cure every defect in the transaction.

Sale of a specific physical portion

Before partition, a co-owner ordinarily has no exclusive title to a definite portion. A purported sale of “the northern 200 square meters,” one house standing on the common lot, or a particular floor therefore requires close review.

The Supreme Court has explained that assigning a definite portion before partition normally requires unanimous consent because it effectively determines in advance which area will belong to the seller. Depending on the facts, the transaction may nevertheless operate only as a transfer of the seller’s undivided share, subject to what the seller ultimately receives in partition. The buyer bears the risk that the described area will not be allotted to the seller.

Sale of more than the seller’s actual share

A co-owner cannot convey better or greater ownership than they possess. If a person owns one-fourth but sells one-half, the deed generally cannot prejudice the other co-owners beyond the seller’s one-fourth interest.

The size of an heir’s share may be uncertain until the estate, debts, compulsory shares, representation, and prior transfers are properly resolved. A percentage stated by the seller should not be accepted without checking the title and succession documents.

Important exceptions and related situations

Community or conjugal property

Co-ownership rules should not automatically be applied to property belonging to an absolute community or conjugal partnership.

Under Articles 96 and 124 of the Family Code, disposition or encumbrance of community or conjugal property generally requires the other spouse’s written consent or court authority. A transaction made without the required consent or authority is treated by the Family Code as void but as a continuing offer that may become binding if accepted by the other spouse or authorized by the court before withdrawal.

Older transactions may be governed by different Civil Code rules. The date of marriage, date of acquisition, date of sale, marriage settlements, and source of funds can materially change the analysis.

Unsettled inherited property

Before an inherited property is partitioned, heirs generally hold undivided interests in the estate. An heir may ordinarily transfer their hereditary or undivided interest, but cannot unilaterally select and convey a particular physical part as exclusively theirs.

Confirm first that the seller is an heir and determine whether there are other heirs, a surviving spouse, an existing will, estate debts, prior waivers, or pending settlement proceedings. A deed signed by only some heirs cannot validly partition or dispose of another heir’s share.

Existing partition

If the property was already validly partitioned—through an enforceable extrajudicial agreement or a final court judgment—the former co-owner may sell the specific property allotted to them, subject to title, tax, registration, and other legal requirements.

Forgery, impersonation, or falsified authority

Article 493 does not validate a forged deed, fabricated signature, fake special power of attorney, or sale by someone who is not an owner. Under Section 53 of Presidential Decree No. 1529, registration obtained through a forged duplicate title, forged deed, or forged instrument is null and void. Later rights claimed by other parties can create difficult land-registration issues, so immediate action is important.

The remaining co-owners’ right of legal redemption

Article 1620 of the Civil Code allows a co-owner to redeem a share sold to a third person. Redemption substitutes the qualified co-owner for the buyer on the same terms and conditions of the sale.

Key rules include:

The right generally applies after an onerous transfer, such as a sale, to someone outside the co-ownership.
The redemptioner ordinarily must assume the genuine terms of the transaction, not merely reimburse an amount they consider fair.
If the stated price is grossly excessive, Article 1620 permits payment of a reasonable price, but whether a price is grossly excessive is a factual and potentially litigated issue.
If several co-owners redeem, they may do so in proportion to their respective shares.
A co-owner’s redemption right takes priority over the redemption right of an adjoining owner.

The 30-day period

Article 1623 states that legal redemption must be exercised within 30 days from written notice by the prospective vendor or vendor, as applicable. It also provides that the deed should not be recorded unless accompanied by the vendor’s affidavit that written notice was given to all possible redemptioners.

In Spouses Barcellano v. Bañas, G.R. No. 259662, April 23, 2025, the Supreme Court clarified the importance of written notice for starting the 30-day period. The notice need not follow a special form, but it should communicate the sale and its material particulars in writing. Receipt of a copy of the deed may qualify.

Because a missed period can defeat redemption, do not rely on verbal statements, social-media posts, neighborhood information, or an uncertain date of discovery. Preserve proof of when any letter, deed, email, message, or other written notice was received.

What to do if your co-owner sold a share

Obtain a fresh certified copy of the title. Request the current transfer certificate of title or original certificate of title and relevant annotations from the Registry of Deeds. Check the registered owners, shares stated, liens, adverse claims, and recent entries.
Secure the deed and registration records. Obtain the deed of sale, vendor’s affidavit of notice, entry details, tax documents, and any special power of attorney used. Do not rely only on photographs or an unsigned draft.
Identify exactly what was sold. Determine whether the deed covers an undivided percentage, a specific area, a building, or the entire property. Compare the technical description with the title and any subdivision or partition plan.
Confirm the seller’s actual share. Review deeds, estate-settlement documents, marriage records, court orders, wills, tax declarations, and prior titles. The percentage shown in a private document may not be legally correct.
Record the notice date. If redemption may be available, keep the envelope, registry receipt, courier tracking, email headers, acknowledgment receipt, and complete copy of the notice. The 30-day period is short.
Have the redemption amount and method evaluated promptly. A valid exercise of redemption normally requires a genuine, timely offer to comply with the sale’s lawful terms. If the buyer or seller refuses to disclose terms or accept payment, a lawyer can assess tender, consignation, and court action.
Send a carefully drafted written response. State your ownership, request complete documents, reserve your rights, and object to any claim over your share or a specific unpartitioned portion. Avoid making admissions about the seller’s share or the deed’s validity before the records are reviewed.
Consider partition if continued co-ownership is unworkable. Article 494 generally allows a co-owner to demand partition. If the parties agree, they may execute a lawful extrajudicial partition. Otherwise, a co-owner may file a judicial action under Rule 69 of the Rules of Court, joining all persons interested in the property. If physical division would cause great prejudice, the court may assign the property to a willing party who pays the others, or order a sale under the conditions in the rule.

Possession after the sale

Buying an undivided share does not automatically authorize the buyer to evict the other co-owners, occupy the whole property exclusively, or fence off the exact area described in the deed.

Each co-owner has a right to possess and use the common property consistently with its purpose and without injuring the other co-owners’ rights. A buyer who replaces the seller generally acquires the same co-ownership rights and limitations.

A dispute over possession is highly fact-specific. A co-owner may have remedies when another co-owner forcibly takes over a portion previously possessed by them, denies the co-ownership, excludes everyone else, destroys improvements, or collects all income without accounting.

Evidence to preserve

Keep originals or reliable certified copies of:

the current and prior certificates of title;
the deed of sale and all annexes;
written notices and proof of receipt;
tax declarations and real-property tax receipts;
subdivision, survey, and partition plans;
estate-settlement documents, wills, and death certificates;
marriage certificates and marriage settlements;
special powers of attorney;
receipts, bank records, and proof of the true purchase price;
messages in which the seller or buyer identifies the property or admits the transaction;
photographs and dated videos showing occupancy, fences, structures, and boundary markers;
lease agreements and records of rent or income;
barangay or police reports concerning threats, entry, damage, or dispossession; and
Registry of Deeds entry numbers, official receipts, and certified registration records.

Preserve complete files, not cropped screenshots. Do not alter electronic evidence.

Registration and taxes

A notarized deed does not by itself resolve whether the seller owned the interest described. For registered land, the parties ordinarily must complete BIR requirements, obtain an electronic Certificate Authorizing Registration, pay applicable local transfer tax and registration fees, and present the required instruments to the Registry of Deeds.

Tax treatment depends on whether the property is a capital asset or ordinary asset and on the nature of the transfer. For a taxable sale of Philippine real property classified as a capital asset, the seller ordinarily files and pays capital gains tax using BIR Form 1706 within 30 days after the sale. Documentary stamp tax is generally filed within five days after the close of the month in which the taxable document was made or transferred. Confirm the current requirements and appropriate revenue district through the BIR’s official capital-gains-tax guidance, BIR forms page, and current eCAR documentary checklist.

These tax deadlines do not extend the 30-day civil-law redemption period.

Common mistakes

Assuming every sale without the other co-owners’ signatures is entirely void.
Treating an undivided percentage as a fixed physical area.
Believing that the person holding the owner’s duplicate title necessarily owns the entire property.
Ignoring the spouse’s rights or applying ordinary co-ownership rules to conjugal or community property.
Waiting for registration before investigating a possible redemption claim.
Relying on oral notice when the date and contents of written notice are disputed.
Paying the seller without checking the title, estate records, annotations, and authority to sell.
Building, fencing, demolishing, or evicting occupants before partition and possession rights are settled.
Signing a waiver, conformity, settlement, or barangay agreement without understanding whether it admits the sale’s validity.
Assuming a tax declaration proves ownership. It may be evidence, but it is not conclusive title.

When legal help is urgent

Consult a Philippine property lawyer immediately if:

you received written notice of sale and may wish to redeem;
registration, subdivision, resale, construction, or demolition is underway;
signatures, notarization, authority, or the owner’s duplicate title may be forged;
the buyer is fencing the property or excluding occupants;
the deed sells the whole property or a defined area despite an unresolved co-ownership;
minors, missing heirs, an unsettled estate, or a deceased registered owner are involved;
the property may be community or conjugal property;
you are being asked to surrender the title or sign a waiver;
an adverse claim, notice of lis pendens, mortgage, or later transfer may be necessary; or
a court summons, demand letter, ejectment case, or partition complaint has been received.

Do not use self-help, threats, or force to remove a buyer or co-owner. The correct remedy may involve redemption, declaration of rights, annulment or nullity, reconveyance, partition, accounting, injunction, adverse claim, or a possession action, depending on the documents and facts.

Frequently asked questions

Can I stop my co-owner from selling their share?

Usually not if the sale is limited to that co-owner’s genuine undivided interest and no separate restriction applies. You may, however, have a right to redeem after a completed sale to a third person.

Must the seller offer the share to me first?

The Civil Code does not generally give co-owners a statutory right of first refusal before a sale. A separate contract, restriction, or special law may create one. Article 1620 primarily provides legal redemption after the share is sold to a third person.

Does the buyer become owner of the room or area identified in the deed?

Not automatically. Before partition, the buyer generally receives only the seller’s undivided share. Any claim to a definite portion remains subject to the other co-owners’ rights and the eventual partition.

Is the entire deed void if one co-owner sold the whole property?

Not necessarily. Philippine jurisprudence commonly gives the deed effect only up to the seller’s actual undivided share, while protecting the shares of non-consenting owners. Forgery, marital-property rules, lack of ownership, and other defects can produce a different result.

Can a buyer demand partition?

Generally, yes. Once the buyer validly acquires an undivided share, the buyer steps into the seller’s position as co-owner and may ordinarily participate in or seek partition.

Can an heir sell before the estate is settled?

An heir may generally transfer their hereditary or undivided interest, but cannot conclusively sell a specific part as exclusively theirs before proper settlement and partition. The buyer also takes the risk that the seller’s final hereditary share will differ from what was represented.

Does my actual knowledge start the 30-day redemption period?

The Civil Code requires notice in writing. Current Supreme Court guidance emphasizes legally sufficient written notice for commencement of the period, although the form of that writing may vary. Treat any written communication containing the sale’s particulars as potentially time-sensitive and obtain advice immediately.

Can I redeem only part of the share sold?

Ordinarily, redemption substitutes the redemptioner for the buyer under the transaction’s terms. Whether partial redemption is possible depends on what was sold, the shares involved, and whether several qualified co-owners are exercising the right proportionately.

Official legal sources

This article provides general legal information, not legal advice or an attorney-client relationship. Property disputes turn on the deed, title, dates, marital regime, succession records, registration history, possession, and evidence. Official sources and procedures were checked as of September 7, 2026.