The power of taxation is often described as the strongest of all powers of government. It is described as plenary, unlimited, and supreme. Chief Justice Marshall once famously noted that "the power to tax involves the power to destroy." However, in the Philippine legal system, this power is not absolute. It operates within a framework of limitations designed to prevent the "power to destroy" from becoming a reality.

These limitations are categorized into two: Inherent Limitations and Constitutional Limitations.

I. Inherent Limitations

Inherent limitations are those restrictions that exist by the very nature of the power of taxation and the existence of a sovereign state. They do not need to be written in the Constitution to be enforceable; they are co-existent with the state itself.

1. Public Purpose

Taxation is a tool for the survival of the state. Therefore, the proceeds of taxation must be used for the common good or the welfare of the people. If a tax is levied for a purely private interest, it is considered void.

Key Concept: The "Public Purpose" test is broad. As long as the public at large benefits, even if certain private individuals benefit incidentally, the requirement is met.

2. Non-Delegability of the Taxing Power

The power to tax is purely legislative. Under the principle of potestas delegata non delegari potest (what has been delegated cannot be further delegated), the Congress cannot pass this power to other branches of government.

Exception: Under the Constitution, Congress may delegate the power to fix tariff rates and quotas to the President, and the power to create their own sources of revenue to Local Government Units (LGUs).

3. Territoriality (Situs of Taxation)

The state can only tax persons, properties, or rights that are within its jurisdiction. A state cannot tax a subject that is not within its borders without violating the due process rights of the taxpayer.

Situs Rules: For real property, the tax is where the land is located. For personal property, it generally follows the owner (mobilia sequuntur personam), though this is subject to many statutory exceptions.

4. International Comity

Based on the principle of sovereign equality, one state cannot exercise jurisdiction over another. Therefore, the property and income of foreign governments and diplomatic representatives are generally exempt from taxation.

5. Exemption of Government Entities

The government generally does not tax itself. Taxing the agencies of the state would merely involve taking money from one pocket and putting it into another, which is administratively redundant.

Note: This applies to agencies performing governmental functions. Government-Owned and Controlled Corporations (GOCCs) performing proprietary functions are usually subject to tax unless their charter provides otherwise.

II. Constitutional Limitations

These are specific restrictions explicitly provided for in the 1987 Philippine Constitution. They act as the "bill of rights" for the taxpayer.

1. Due Process of Law (Art. III, Sec. 1)

No person shall be deprived of property without due process. In taxation, this means:

The tax must not be confiscatory or oppressive.
The tax must be imposed by a valid law.
The taxpayer must be given an opportunity to be heard (administrative or judicial) in case of assessments.

2. Equal Protection Clause (Art. III, Sec. 1)

All persons subject to legislation shall be treated alike under like circumstances and conditions.

Classification: The state can classify taxpayers (e.g., individuals vs. corporations), provided the classification is based on substantial distinctions, is germane to the purpose of the law, and applies equally to all members of the same class.

3. Uniformity and Equity in Taxation (Art. VI, Sec. 28[1])

The Constitution mandates that "The rule of taxation shall be uniform and equitable. The Congress shall evolve a progressive system of taxation."

Uniformity: All taxable articles or properties of the same class shall be taxed at the same rate.
Equity: Taxation must be based on the taxpayer's ability to pay.
Progressivity: As the income base increases, the tax rate should also increase (e.g., the graduated income tax table).

4. Non-Imprisonment for Non-Payment of Poll Tax (Art. III, Sec. 20)

No person shall be imprisoned for debt or non-payment of a poll tax (such as the Community Tax or "cedula").

Warning: This protection only applies to the poll tax. You can be imprisoned for non-payment of income tax, VAT, or other internal revenue taxes, as these are considered crimes of tax evasion.

5. Exemption of Religious, Charitable, and Educational Institutions (Art. VI, Sec. 28[3])

Charitable institutions, churches, parsonages, or convents appurtenant thereto, mosques, non-profit cemeteries, and all lands, buildings, and improvements actually, directly, and exclusively (ADE) used for religious, charitable, or educational purposes shall be exempt from property tax (Real Property Tax).

6. Non-Impairment of the Obligation of Contracts

A law cannot be passed that impairs the obligations of a valid contract. If the government granted a tax exemption based on a valid contract (and not just a general law), it cannot unilaterally revoke it if such revocation would be inequitable.

III. Summary Table: Inherent vs. Constitutional

Feature	Inherent Limitations	Constitutional Limitations
Source	Nature of State Sovereignty	1987 Constitution
Need for Writing	Exist even if not written	Must be explicitly stated
Primary Goal	Define the scope of tax power	Protect the rights of the citizen
Examples	Public Purpose, Territoriality	Due Process, Uniformity, Equity

The Judicial Safeguard

The Supreme Court of the Philippines acts as the final arbiter in determining whether the state has overstepped these boundaries. While the power to tax is indeed the "lifeblood of the government," the courts ensure that this lifeblood is not extracted at the cost of the fundamental liberties of the people. As Justice Holmes famously countered Marshall's dictum: "The power to tax is not the power to destroy while this Court sits."