Below is a concise‐but‐complete legal primer on Philippine estate taxation when the estate includes untitled (unregistered) real property. It is written as an article that you may quote or adapt. I have avoided online research and relied on the National Internal Revenue Code (NIRC), Bureau of Internal Revenue (BIR) issuances, and landmark jurisprudence that lawyers routinely cite.

1. Why “untitled” land is common—and why estates trigger special issues

Spanish‑time grants & possessory rights. Large tracts were never issued Torrens certificates. Owners merely possess tax declarations or deeds of sale.
Title vs. ownership. In the Philippines, registration is not the source of ownership (Art. 433 Civil Code); it only confirms it. Thus heirs can inherit unregistered land, but proving value and ownership to the BIR requires extra documents.
Estate tax attaches to all “property, real or personal, tangible or intangible, wherever situated” (NIRC §84). There is no exception just because the land lacks a Torrens title.

2. Core statutes and regulations

Reference	Key point for untitled property
NIRC §§84–97	Defines gross estate, deductions, rates, filing, and payment.
NIRC §88	Valuation: Fair Market Value (FMV) is the higher of (a) zonal valuation or (b) current tax declaration. If no zonal valuation has been issued, the Assessor’s tax declaration controls, subject to BIR review.
Rev. Regs. No. 12‑2018	Consolidated estate tax rules under TRAIN (6 % flat rate).
Revenue Memorandum Circular (RMC) 60‑2019, as amended	Documentary checklist for estates with untitled real property.
Estate Tax Amnesty Law (RA 11213, extended by RA 11569 and RA 11956)	Reduces estate tax to 6 % of net undeclared estate per decedent for those who died ≤ 14 June 2021, with payment deadline now 14 June 2025. Applies even if properties are untitled.

3. Acceptable proof of ownership

For each untitled parcel the BIR will typically require all of the following (plus one photocopy each):

Latest certified true copy of the Tax Declaration from the Municipal/City Assessor.
Real Property Tax (RPT) clearances for the past 5 years.
Sworn Declaration of No Title/Certification of No Existing Title from the Registry of Deeds.
Lot plan & vicinity map prepared and signed by a licensed Geodetic Engineer (approved by DENR‑LMB if over 1 ha or if needed for subdivision).
Proof of acquisition cost (e.g., deed of sale, Extrajudicial Settlement with sale, or mother deed if any).
Affidavit of Self‑Adjudication or Extrajudicial Settlement of Estate (EJS), notarized and published once a week for 3 weeks in a newspaper of general circulation (Rule 74, Rules of Court).

4. Valuation rules specific to untitled land

Use the assessor’s current market value if the BIR has not issued a zonal value for the barangay.
Partial zonal coverage: If a zonal value exists for a neighboring titled lot of the same classification, the BIR may adopt that value by analogy.
Easements, actual use, and improvements must be substantiated (e.g., residential vs. agricultural) by photos and assessor’s certifications.
No “discount” for lack of title: The BIR considers market value, not liquidity—so untitled status does not reduce the tax base.

5. Filing & payment procedure (standard vs. amnesty)

A. Regular estate tax (deaths on or after 1 Jan 2018)

File BIR Form 1801 within one year from decedent’s death (NIRC §90), at the Revenue District Office (RDO) where the decedent was domiciled.
Attach the documentary bundle in § 3.
Pay 6 % of the net taxable estate (FMV less allowable deductions such as family home up to ₱10 M, standard deduction ₱5 M, funeral/medical expenses ceilings).
Secure Electronic Certificate Authorizing Registration (eCAR) for each parcel. Without a title, the eCAR will reference the lot description and tax declaration number.
Register the settlement: Present eCAR and EJS to the Registry of Deeds to obtain Original Certificate of Title (OCT) in heirs’ names or to annotate ownership on the tax declaration if they do not yet pursue titling.

B. Estate tax amnesty (deaths up to 14 June 2021)

File BIR Form 2118‑E and the Estate Amnesty Return until 14 June 2025.
Pay 6 % of the decedent’s net undeclared estate—no incremental penalties, surcharges, or interest.
Submit a Statement of Settlement of Estate (simpler than full EJS) and tax declaration.
Upon payment, secure Certificate of Availment and eCAR.
Proceed with titling or transfer. For large, untitled tracts this is often the cleanest path.

6. When heirs disagree or can’t locate documents

Scenario	Practical solution
Co‑heir refuses to sign EJS or BIR forms	File a petition for settlement with the Regional Trial Court (special proceeding). The court order plus a project of partition substitutes for voluntary EJS.
Missing tax declarations	Request reconstruction from the Assessor and attach an Affidavit of Loss.
Overlap/conflict with titled land	File an accion reivindicatoria or reconstitution case; estate tax payment may still proceed but annotate dispute on the eCAR.

7. Penalties, interest, and non‑payment risks

Surcharge: 25 % of the basic tax if late (or 50 % if due to willful neglect or false return, NIRC §248).
Interest: 20 % p.a. (simple) until paid (NIRC §249).
No eCAR = no registration. LGUs will not transfer RPT records, and heirs cannot mortgage or sell.
Criminal liability: Rare in practice, but NIRC §255 penalizes willful refusal to file/pay.

8. Key jurisprudence

Heirs of Malate v. Gamboa, G.R. 168726 (23 Jan 2013) – Untitled land may be part of the estate even if occupied by another; BIR valuation takes priority over occupancy questions.
Commissioner v. Court of Appeals & S.P. Properties, G.R. 108576 (14 Jan 1999) – Zonal valuation prevails over lower municipal assessments.
Demanes v. BIR, CTA EB 1557 (27 Jan 2021) – The BIR cannot refuse eCAR issuance solely because land is untitled if taxpayer submits complete alternative proofs.

9. Practical checklist for practitioners

Gather documents early: Heirs often spend months retrieving assessor records.
Secure BIR certification of “No Zonal Value” if applicable.
Use the amnesty if eligible—it wipes pre‑2018 surcharges & interest, and documentation demands are lighter.
Budget for documentary stamp tax (DST) on the EJS (₱15.00 per ₱1,000 of FMV).
Pay real‑property taxes current; LGUs require this before accepting transfer.
Engage a geodetic survey when boundaries are unclear—critical before titling.

10. Frequently asked questions

Question	Short answer
Does the six‑year prescriptive period to assess apply?	Yes, but only if a return is filed. Filing late still starts the clock (NIRC §203). No return = no prescription.
Can we pay estate tax first and do the EJS later?	Under RMC 34‑2017 & 60‑2019, the BIR will accept a Sworn Declaration of Heirs and issue a provisional eCAR, but you must submit the final EJS within 2 years.
*What if there is no zonal value and* the tax declaration is decades old?**	The RDO will often direct the Assessor to update the schedule of values or require a bank appraisal as substitute FMV.
Is title rehabilitation (PD 1529) required before eCAR?	No. Estate tax is separate from land registration; you may settle taxes first, then pursue judicial titling.

Closing note

Estate tax on untitled property is largely a paper chase: the economic cost is now a flat 6 %, but assembling credible evidence of ownership and FMV is where estates succeed or stall. Early document gathering, strategic use of the Estate Tax Amnesty, and, when necessary, court intervention remain the best practices.

This article is for general guidance only and does not substitute for tailored legal advice from a Philippine tax counsel or estate practitioner.