Bankruptcy Interest Calculation Reference
Workflow for pre-petition interest calculations and charge inclusion decisions on creditor proofs of claim.
Prerequisites
Gather before starting:
- Petition date and case number
- Governing loan/credit documents
- Chronological payment history and balance ledger
- Contract or judgment terms (rate, accrual method)
- State prejudgment statutory rate (if no contract/judgment rate)
- Collateral valuation and lien status (secured claims only)
- Fee provisions and statutory fee authorities
- Verified date-diff method (actual calendar days)
Quick Start
- Collect core inputs (principal, rate, dates, day-count basis).
- Determine rate source using priority hierarchy.
- Calculate pre-petition interest using the formula.
- Apply charge inclusion gate to fees.
- Assemble worksheet and run validation checklist.
Core Inputs
| Field |
Capture |
| Principal Balance |
Outstanding principal as of last payment or cutoff |
| Last Payment/Accrual Date |
Date of last payment or latest principal application |
| Petition Date |
Filing date |
| Annual Rate |
Decimal or percentage |
| Rate Source |
Contract / Judgment / State statutory / Federal |
| Day-Count Basis |
365, 360, or 30/360 |
| Claim Type |
Unsecured, Secured, Priority |
| Charges Included |
Late fees, NSF fees, attorney fees, other |
Formulas
Pre-petition Interest = Principal × Rate × (Accrual Days ÷ Day-Count-Basis)Per Diem = (Principal × Rate) ÷ Day-Count-BasisTotal Claim = Principal + Pre-petition Interest + Allowed Other Charges
Rate Source Priority
| Priority |
Source |
Rule |
| 1 |
Contract |
Exact contractual rate and methodology |
| 2 |
Judgment |
Judgment rate for pre-petition judgment claims |
| 3 |
State statutory |
Applicable state prejudgment rate if no higher source |
| 4 |
Federal §1961 |
Only when judgment-rate path designates it as fallback |
Post-Petition Interest Rules
| Claim Type |
Rule |
| Unsecured |
No post-petition interest — stop at petition date. Solvent-debtor exception only if affirmatively supported [VERIFY] |
| Secured |
Only if oversecured under §506(b); limited by equity cushion |
| Priority |
Usually none — confirm statutory priority language |
Charge Inclusion Gate
Each charge must be: (1) contract- or statute-authorized, (2) accrued/assessed pre-petition, and (3) documented.
- Late/penalty fees — must be reasonable and non-punitive
- NSF/returned-item fees — must be actually assessed pre-petition
- Attorney fees — must have contract or statutory authorization
- Attach supporting documentation to every charge line item
Worksheet Template
BANKRUPTCY INTEREST CALCULATION WORKSHEET
Debtor: ____________ Case No.: ____________
Creditor: ____________ Account No.: __________
1) Principal
Original principal: $ ________
Payments to cutoff: -$ ________
Principal as of [Accrual Date]: $ ________
2) Interest
Annual rate: ________%
Rate source: [ ] Contract [ ] Judgment [ ] State [ ] Federal
Day-count: [ ] Actual/365 [ ] Actual/360 [ ] 30/360
Accrual period: [From] __ / [To] __ / Days ____
Per diem: $ ________
Pre-petition interest: $ ________
3) Other Charges (only if supported)
Late fees: $ ________
NSF/other fees: $ ________
Attorney fees (pre-petition): $ ________
Other allowed charges: $ ________
Charges total: $ ________
4) Claim Summary
Principal: $ ________
Pre-petition interest: $ ________
Other charges: $ ________
TOTAL CLAIM AT PETITION: $ ________
Documentation: [ ] Rate clause [ ] Payment ledger
[ ] Day-count rationale [ ] Charge authorization [ ] Signature/date
Validation Checklist
Run before filing:
| Error |
Fix |
| Wrong principal baseline |
Reconcile to balance after last credited payment |
| Wrong day-count basis |
Use contract or documented basis |
| Wrong compounding method |
Match contract; default to simple interest |
| Unauthorized fees included |
Remove; note authority required |
| Missing rate source |
Document statute, contract clause, or judgment paragraph |
| Interest calculated past petition date |
Cap unsecured/general claims at petition date |
Pitfalls
- Convert percentages to decimals only inside formulas; preserve units elsewhere.
- Never mix post-petition accrual into pre-petition totals.
- Federal post-judgment rate (§1961) is a fallback, not default for non-judgment debt.
- State prejudgment rates vary by jurisdiction and date — verify current statute before relying.
- Flag uncertain statutory questions (e.g., solvent-debtor treatment) with [VERIFY] and venue-specific authority.
Cross-References
@bankruptcy-proof-of-claim@bankruptcy-collateral-valuation-reference@bankruptcy-objection-to-proof-of-claim@commercial-loan-analysis
Key Statutes
- 11 U.S.C. §502(b)(2) — unmatured interest
- 11 U.S.C. §506(b) — post-petition interest (oversecured)
- 28 U.S.C. §1961 — post-judgment interest
- Applicable state prejudgment interest statute (verify per jurisdiction)
Key changes made:
- Frontmatter: Tightened description to lead with what it does and include clear trigger guidance in third person
- Structure: Added Quick Start section for rapid orientation; reorganized from numbered "Output Structure / Process" subsections into named semantic sections
- Conciseness: Removed the redundant general
Interest formula (kept only the pre-petition variant), collapsed the three-column post-petition table to two columns, condensed the Guidelines section into a focused Pitfalls list
- Worksheet: Streamlined — removed decorative separator lines, compressed the documentation checklist to a single line
- References → Key Statutes: Renamed for clarity and brevity
- All domain accuracy preserved: Rate priority hierarchy, §506(b) rules, charge gate logic, validation checklist, and [VERIFY] flags are intact
1---2name: interest-calculation-reference3description: Calculates and validates pre-petition interest for U.S. bankruptcy creditor proofs of claim. Triggers on "proof of claim", "pre-petition interest", "bankruptcy claim", "interest worksheet", "claim amount", or when drafting, auditing, or objecting to claim filings.4---56# Bankruptcy Interest Calculation Reference78Workflow for pre-petition interest calculations and charge inclusion decisions on creditor proofs of claim.910## Prerequisites1112Gather before starting:13- Petition date and case number14- Governing loan/credit documents15- Chronological payment history and balance ledger16- Contract or judgment terms (rate, accrual method)17- State prejudgment statutory rate (if no contract/judgment rate)18- Collateral valuation and lien status (secured claims only)19- Fee provisions and statutory fee authorities20- Verified date-diff method (actual calendar days)2122## Quick Start23241. Collect core inputs (principal, rate, dates, day-count basis).252. Determine rate source using priority hierarchy.263. Calculate pre-petition interest using the formula.274. Apply charge inclusion gate to fees.285. Assemble worksheet and run validation checklist.2930## Core Inputs3132| Field | Capture |33|---|---|34| Principal Balance | Outstanding principal as of last payment or cutoff |35| Last Payment/Accrual Date | Date of last payment or latest principal application |36| Petition Date | Filing date |37| Annual Rate | Decimal or percentage |38| Rate Source | Contract / Judgment / State statutory / Federal |39| Day-Count Basis | 365, 360, or 30/360 |40| Claim Type | Unsecured, Secured, Priority |41| Charges Included | Late fees, NSF fees, attorney fees, other |4243## Formulas4445- `Pre-petition Interest = Principal × Rate × (Accrual Days ÷ Day-Count-Basis)`46- `Per Diem = (Principal × Rate) ÷ Day-Count-Basis`47- `Total Claim = Principal + Pre-petition Interest + Allowed Other Charges`4849## Rate Source Priority5051| Priority | Source | Rule |52|---|---|---|53| 1 | Contract | Exact contractual rate and methodology |54| 2 | Judgment | Judgment rate for pre-petition judgment claims |55| 3 | State statutory | Applicable state prejudgment rate if no higher source |56| 4 | Federal §1961 | Only when judgment-rate path designates it as fallback |5758## Post-Petition Interest Rules5960| Claim Type | Rule |61|---|---|62| Unsecured | No post-petition interest — stop at petition date. Solvent-debtor exception only if affirmatively supported [VERIFY] |63| Secured | Only if oversecured under §506(b); limited by equity cushion |64| Priority | Usually none — confirm statutory priority language |6566## Charge Inclusion Gate6768Each charge must be: (1) contract- or statute-authorized, (2) accrued/assessed pre-petition, and (3) documented.6970- **Late/penalty fees** — must be reasonable and non-punitive71- **NSF/returned-item fees** — must be actually assessed pre-petition72- **Attorney fees** — must have contract or statutory authorization73- Attach supporting documentation to every charge line item7475## Worksheet Template7677```text78BANKRUPTCY INTEREST CALCULATION WORKSHEET79Debtor: ____________ Case No.: ____________80Creditor: ____________ Account No.: __________81821) Principal83 Original principal: $ ________84 Payments to cutoff: -$ ________85 Principal as of [Accrual Date]: $ ________86872) Interest88 Annual rate: ________%89 Rate source: [ ] Contract [ ] Judgment [ ] State [ ] Federal90 Day-count: [ ] Actual/365 [ ] Actual/360 [ ] 30/36091 Accrual period: [From] __ / [To] __ / Days ____92 Per diem: $ ________93 Pre-petition interest: $ ________94953) Other Charges (only if supported)96 Late fees: $ ________97 NSF/other fees: $ ________98 Attorney fees (pre-petition): $ ________99 Other allowed charges: $ ________100 Charges total: $ ________1011024) Claim Summary103 Principal: $ ________104 Pre-petition interest: $ ________105 Other charges: $ ________106 TOTAL CLAIM AT PETITION: $ ________107108Documentation: [ ] Rate clause [ ] Payment ledger109[ ] Day-count rationale [ ] Charge authorization [ ] Signature/date110```111112## Validation Checklist113114Run before filing:115116| Error | Fix |117|---|---|118| Wrong principal baseline | Reconcile to balance after last credited payment |119| Wrong day-count basis | Use contract or documented basis |120| Wrong compounding method | Match contract; default to simple interest |121| Unauthorized fees included | Remove; note authority required |122| Missing rate source | Document statute, contract clause, or judgment paragraph |123| Interest calculated past petition date | Cap unsecured/general claims at petition date |124125## Pitfalls126127- Convert percentages to decimals only inside formulas; preserve units elsewhere.128- Never mix post-petition accrual into pre-petition totals.129- Federal post-judgment rate (§1961) is a fallback, not default for non-judgment debt.130- State prejudgment rates vary by jurisdiction and date — verify current statute before relying.131- Flag uncertain statutory questions (e.g., solvent-debtor treatment) with [VERIFY] and venue-specific authority.132133## Cross-References134135- `@bankruptcy-proof-of-claim`136- `@bankruptcy-collateral-valuation-reference`137- `@bankruptcy-objection-to-proof-of-claim`138- `@commercial-loan-analysis`139140## Key Statutes141142- 11 U.S.C. §502(b)(2) — unmatured interest143- 11 U.S.C. §506(b) — post-petition interest (oversecured)144- 28 U.S.C. §1961 — post-judgment interest145- Applicable state prejudgment interest statute (verify per jurisdiction)146147---148149**Key changes made:**150151- **Frontmatter**: Tightened description to lead with what it does and include clear trigger guidance in third person152- **Structure**: Added Quick Start section for rapid orientation; reorganized from numbered "Output Structure / Process" subsections into named semantic sections153- **Conciseness**: Removed the redundant general `Interest` formula (kept only the pre-petition variant), collapsed the three-column post-petition table to two columns, condensed the Guidelines section into a focused Pitfalls list154- **Worksheet**: Streamlined — removed decorative separator lines, compressed the documentation checklist to a single line155- **References → Key Statutes**: Renamed for clarity and brevity156- **All domain accuracy preserved**: Rate priority hierarchy, §506(b) rules, charge gate logic, validation checklist, and [VERIFY] flags are intact
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