1) The core idea: what “interest capitalization” really means
Interest capitalization is the practice of adding unpaid, already-due interest to the outstanding principal, so that the borrower thereafter pays interest on the increased principal. In everyday lending, this shows up in several ways:
- Compounding / “interest on interest” (anatocism): unpaid interest becomes part of principal (or otherwise becomes interest-bearing), causing total debt to grow faster than under simple interest.
- Restructuring / renewal / refinancing: accrued but unpaid interest is rolled into a new principal under a new (or amended) written agreement; future interest is computed on that new principal.
- Litigation and judgments: once amounts are judicially demanded or reduced to judgment, the law allows interest to run in specific ways that can resemble compounding.
In Philippine law, the legality turns less on the label (“capitalization,” “compounding,” “add-on”) and more on (a) whether the interest is validly stipulated in writing, (b) whether interest-on-interest is expressly permitted by written agreement or by law, and (c) whether the resulting charges are enforceable as a matter of fairness and public policy.
2) Legal foundation: interest is not presumed, and it must be in writing
A starting rule in the Civil Code is strict:
A. No interest unless expressly stipulated in writing
Civil Code, Article 1956 provides that no interest is due unless it has been expressly stipulated in writing.
Practical consequences:
- If a lender claims “we agreed verbally to 5% monthly,” that interest is generally not collectible as contractual interest (though legal interest as damages may apply after default in some situations—see Section 6).
- If the loan document is silent or ambiguous on interest, courts often treat it as non-interest bearing as a contractual matter.
B. Capitalization is “interest-on-interest,” so it needs its own legal basis
Capitalization typically makes unpaid interest earn interest, which is classically called anatocism. Philippine law treats anatocism as generally disfavored unless the Civil Code conditions are met.
3) The Philippine rule on “interest-on-interest” (anatocism)
The Civil Code sets the baseline:
A. General prohibition, with defined exceptions
Civil Code, Article 1959 (read together with Article 2212) is the usual framework:
- As a general rule: interest due and unpaid does not earn interest.
- Exception 1 — Express written stipulation (contractual capitalization): the parties may agree in writing that due and unpaid interest will earn interest (i.e., be capitalized / compounded).
- Exception 2 — Judicial demand (legal interest-on-interest): Civil Code, Article 2212 allows interest due to earn legal interest from the time it is judicially demanded, even if the contract is silent on interest-on-interest.
Key points embedded in these rules:
- The interest must be due (not merely accruing in the abstract).
- Capitalization must be express and in writing (contractual route), or triggered by judicial demand (legal route).
4) When adding unpaid interest to principal is generally legal
Scenario A: The loan contract clearly authorizes capitalization in writing
A clause may validly provide, for example, that:
- interest is payable monthly/quarterly, and
- any interest unpaid when due shall be added to principal and bear interest at the agreed rate (or at a specified rate).
When this is enforceable:
- The clause is clear, written, and mutually agreed.
- The capitalization applies only to interest that has become due under the contract’s schedule.
Common lawful forms
- Periodic compounding: “interest payable monthly; unpaid interest shall be capitalized monthly.”
- Default capitalization: “upon default, any unpaid interest shall be added to the outstanding principal.”
Scenario B: The parties execute a written restructuring/renewal that rolls unpaid interest into a new principal (novation or modification)
Even where the original contract did not provide for compounding, parties sometimes later agree—in writing—to:
- compute the arrears (principal + accrued interest + charges),
- set that sum as a new principal under a renewed promissory note or restructured loan, and
- apply a new rate and schedule.
This can be legally defensible if:
- there is genuine mutual consent (not unilateral bank action),
- the borrower’s assent is documented, and
- required disclosures (especially for consumer credit) are complied with.
Scenario C: The lender files a collection case, and “interest due” is judicially demanded
Under Article 2212, once interest due is judicially demanded, it may earn legal interest from that time. This is a statutory path to interest-on-interest that does not require a capitalization clause.
Scenario D: Post-judgment interest on the adjudged amount
After a court issues a money judgment that becomes final, Philippine doctrine generally treats the adjudged sum as earning legal interest until full satisfaction (the Supreme Court’s modern framework traces through Eastern Shipping Lines and later Nacar v. Gallery Frames guidelines). This is not “contractual compounding,” but it produces a similar economic effect: the total due grows over time if unpaid.
5) When adding unpaid interest to principal is generally illegal or unenforceable
A. Unilateral capitalization without a written agreement
If the lender simply posts a ledger entry—“we added your unpaid interest to your principal”—and then charges interest on that higher base without an express written capitalization agreement, the borrower has a strong argument that:
- it is prohibited anatocism under Article 1959, absent the legal exception of judicial demand under Article 2212.
B. No valid written stipulation of interest at all
If interest itself was not validly stipulated in writing (Article 1956), capitalization collapses with it:
- there is nothing valid to capitalize as contractual interest.
- the lender may still claim legal interest as damages after default in proper cases (Section 6), but that is different from “capitalized contractual interest.”
C. Capitalization that effectively lets one party control the contract (lack of mutuality)
Civil Code, Article 1308 prohibits leaving the validity or compliance of a contract to the will of one party.
Problems arise when capitalization is tied to unilateral discretion, such as:
- “Lender may, at its option, capitalize any amounts it deems unpaid, at any time, at rates it determines.”
Even if a contract mentions capitalization, a court may scrutinize whether the mechanism:
- is objective, determinable, and
- does not allow unilateral rewriting of the bargain.
D. Unconscionable interest, penalties, or combined charges (even if written)
Since the lifting of interest ceilings (commonly associated with CB Circular No. 905), Philippine courts have still repeatedly held that unconscionable or iniquitous interest and penalties may be:
- reduced, or
- in extreme cases, struck down and replaced with legal interest standards.
Capitalization magnifies effective rates. Even a rate that looks tolerable under simple interest can become oppressive when compounded frequently, combined with default interest, penalties, and fees.
E. Penalty clauses stacked with capitalized interest
Loans often impose multiple layers:
- compensatory interest (for use of money),
- moratory/default interest (for delay),
- penalty charges/liquidated damages,
- attorney’s fees and costs.
Courts may reduce penalties under Civil Code, Article 1229 when iniquitous or unconscionable, and may examine whether the combined effect is excessive—especially if penalties are computed on amounts that include capitalized interest.
F. Disclosure failures in consumer loans (Truth in Lending)
For consumer credit, RA 3765 (Truth in Lending Act) and related regulations require clear disclosure of finance charges and effective costs. Capitalization affects:
- the effective interest rate,
- the amortization schedule,
- the total finance charge.
When required disclosures are missing or misleading, enforceability and remedies can be affected, and liability may attach depending on the violation and context.
6) Distinguishing types of interest that often get confused in capitalization disputes
Understanding what kind of “interest” is being added or charged is crucial.
A. Compensatory interest (contract interest)
This is the price for the use of money during the loan term. It must be expressly stipulated in writing (Art. 1956).
B. Moratory interest (delay/default interest) as damages
When a borrower is in delay in paying a sum of money, Civil Code, Article 2209 provides that damages are generally measured by:
- the interest agreed upon, or
- in the absence of stipulation, the legal interest.
This is conceptually damages for delay, not the original “price of money.”
C. Interest on interest (anatocism)
This is where Article 1959 and Article 2212 become central. If a lender is charging interest on overdue interest, one asks:
- Is there an express written stipulation permitting it?
- Or has there been judicial demand triggering Article 2212?
D. Legal interest rate (when courts apply it)
The Philippine legal interest landscape changed historically (often discussed in relation to Central Bank/BSP issuances and Supreme Court guidelines). Since July 1, 2013, the commonly applied legal interest rate in many contexts has been 6% per annum, subject to BSP adjustments and the governing doctrine for the particular obligation. Capitalization disputes often end with courts recomputing obligations using legal interest standards—especially when contractual rates/charges are void or unconscionable.
7) Application of payments: why borrowers think they’re paying principal but aren’t
A frequent flashpoint is how payments are allocated when there is interest.
Civil Code, Article 1253 provides that if a debt produces interest, payment of the principal shall not be deemed made until the interests have been covered, unless there is a contrary stipulation.
Practical effect:
- If a borrower pays “₱10,000 for principal,” the law may still treat that payment as going first to interest arrears.
- This is separate from capitalization. Even without capitalization, unpaid interest can consume later payments first.
This is why borrowers sometimes see principal barely reduce and conclude the lender “capitalized” interest; sometimes it is simply statutory application of payments plus ongoing interest accrual.
8) Common real-world loan structures and where capitalization hides
A. Amortizing loans with missed installments
In installment loans, each payment is typically composed of:
- interest portion, then
- principal portion.
When payments are missed:
- interest continues to accrue,
- penalties may be added,
- some lenders capitalize arrears (if allowed), making subsequent interest larger.
Key question: Does the written contract authorize capitalization of due and unpaid interest?
B. “Past due interest” and “capitalized interest” entries
Statements of account may show:
- Accrued interest (not yet due)
- Past due interest (due but unpaid)
- Capitalized interest (added to principal)
- Penalty charges and fees
Only the “capitalized interest” step (and charging interest on that amount) squarely triggers anatocism concerns.
C. Credit facilities and revolving credit
Revolving products may compute finance charges on outstanding balances that may already include prior charges depending on terms. The legal analysis still comes back to:
- written agreement,
- disclosures,
- unconscionability,
- and whether interest-on-interest is truly occurring or the “balance” is treated as a single evolving principal by contract.
9) Litigation playbook: how capitalization disputes are typically resolved
A. What courts commonly examine
The promissory note/loan agreement:
- Is interest stipulated in writing? (Art. 1956)
- Is capitalization expressly authorized in writing? (Art. 1959)
Demand and default timeline:
- When did interest become due?
- Was there judicial demand? (Art. 2212)
Statements of account and computation method:
- Was interest charged on unpaid interest?
- How often was compounding applied?
- Are penalties computed on principal only or on amounts including interest?
Reasonableness / unconscionability:
- Total effective burden (interest + penalty + fees), especially after compounding.
B. Typical judicial outcomes
- Disallow capitalization where no clear written stipulation exists, and recompute using simple interest and/or legal interest rules.
- Reduce unconscionable rates and penalties; sometimes replace void interest stipulations with legal interest as damages from demand.
- Apply legal interest on “interest due” from the time of judicial demand (Art. 2212) where applicable.
- Apply post-judgment interest on the adjudged sum until full payment.
C. Evidence that matters most
- Signed promissory note / credit agreement and all riders/amendments.
- Disclosure statements (especially for consumer credit).
- Detailed statement of account / amortization schedule showing how the lender computed interest.
- Demand letters and proof of receipt.
- Court pleadings (date of filing matters for Article 2212 issues).
10) Illustrations: simple vs capitalized interest
Example 1: Simple interest (no capitalization)
- Principal: ₱100,000
- Interest: 12% per annum, payable at maturity (1 year)
- If unpaid at 1 year: interest due = ₱12,000 Total due at maturity: ₱112,000 If lender does not capitalize, later interest (if any) should be computed as allowed by contract or by law, but not automatically on the ₱12,000 unless Article 1959 or 2212 applies.
Example 2: Contractual capitalization (written clause)
Same loan, but contract says:
- “Interest payable monthly; unpaid interest shall be added to principal monthly.” If the borrower pays nothing, the principal base increases monthly, and total due becomes higher than ₱112,000 at year end, because interest is being charged on prior unpaid interest by agreement.
Example 3: Judicial demand triggers legal interest on interest due
- Borrower owes ₱12,000 interest that is already due.
- Lender files a collection case demanding payment. From the time of judicial demand, the interest due may itself earn legal interest under Article 2212.
11) Practical compliance checklist for lawful capitalization (Philippine context)
For capitalization to be on the safest ground, documentation typically needs to show:
Interest is expressly stipulated in writing (Art. 1956).
Interest is defined clearly (rate, basis, frequency, when due).
Capitalization is expressly stipulated in writing (Art. 1959), including:
- what counts as “unpaid interest,”
- when it becomes “due,”
- when capitalization occurs (monthly/quarterly/upon default),
- what rate applies after capitalization.
No unilateral discretion that violates mutuality (Art. 1308).
Penalties are not oppressive and may be defensible under equitable reduction standards (Art. 1229).
Consumer credit disclosures accurately reflect effective cost (Truth in Lending).
12) Key takeaways
In the Philippines, adding unpaid interest to principal and then charging interest on that enlarged amount is generally not allowed unless:
- there is an express written stipulation allowing capitalization (Civil Code Art. 1959), or
- interest due has been judicially demanded, allowing legal interest on that interest (Civil Code Art. 2212).
No interest is collectible as contractual interest unless expressly stipulated in writing (Civil Code Art. 1956).
Even when written, capitalization and stacked charges remain vulnerable if unconscionable, if they violate mutuality, or if required consumer disclosures are defective.
Many disputes are resolved by recomputing the obligation: disallowing unauthorized capitalization, reducing excessive charges, and applying legal interest rules based on demand and judgment timelines.