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.4license: Apache-2.05---67# Bankruptcy Interest Calculation Reference89Workflow for pre-petition interest calculations and charge inclusion decisions on creditor proofs of claim.1011## Prerequisites1213Gather before starting:14- Petition date and case number15- Governing loan/credit documents16- Chronological payment history and balance ledger17- Contract or judgment terms (rate, accrual method)18- State prejudgment statutory rate (if no contract/judgment rate)19- Collateral valuation and lien status (secured claims only)20- Fee provisions and statutory fee authorities21- Verified date-diff method (actual calendar days)2223## Quick Start24251. Collect core inputs (principal, rate, dates, day-count basis).262. Determine rate source using priority hierarchy.273. Calculate pre-petition interest using the formula.284. Apply charge inclusion gate to fees.295. Assemble worksheet and run validation checklist.3031## Core Inputs3233| Field | Capture |34|---|---|35| Principal Balance | Outstanding principal as of last payment or cutoff |36| Last Payment/Accrual Date | Date of last payment or latest principal application |37| Petition Date | Filing date |38| Annual Rate | Decimal or percentage |39| Rate Source | Contract / Judgment / State statutory / Federal |40| Day-Count Basis | 365, 360, or 30/360 |41| Claim Type | Unsecured, Secured, Priority |42| Charges Included | Late fees, NSF fees, attorney fees, other |4344## Formulas4546- `Pre-petition Interest = Principal × Rate × (Accrual Days ÷ Day-Count-Basis)`47- `Per Diem = (Principal × Rate) ÷ Day-Count-Basis`48- `Total Claim = Principal + Pre-petition Interest + Allowed Other Charges`4950## Rate Source Priority5152| Priority | Source | Rule |53|---|---|---|54| 1 | Contract | Exact contractual rate and methodology |55| 2 | Judgment | Judgment rate for pre-petition judgment claims |56| 3 | State statutory | Applicable state prejudgment rate if no higher source |57| 4 | Federal §1961 | Only when judgment-rate path designates it as fallback |5859## Post-Petition Interest Rules6061| Claim Type | Rule |62|---|---|63| Unsecured | No post-petition interest — stop at petition date. Solvent-debtor exception only if affirmatively supported [VERIFY] |64| Secured | Only if oversecured under §506(b); limited by equity cushion |65| Priority | Usually none — confirm statutory priority language |6667## Charge Inclusion Gate6869Each charge must be: (1) contract- or statute-authorized, (2) accrued/assessed pre-petition, and (3) documented.7071- **Late/penalty fees** — must be reasonable and non-punitive72- **NSF/returned-item fees** — must be actually assessed pre-petition73- **Attorney fees** — must have contract or statutory authorization74- Attach supporting documentation to every charge line item7576## Worksheet Template7778```text79BANKRUPTCY INTEREST CALCULATION WORKSHEET80Debtor: ____________ Case No.: ____________81Creditor: ____________ Account No.: __________82831) Principal84 Original principal: $ ________85 Payments to cutoff: -$ ________86 Principal as of [Accrual Date]: $ ________87882) Interest89 Annual rate: ________%90 Rate source: [ ] Contract [ ] Judgment [ ] State [ ] Federal91 Day-count: [ ] Actual/365 [ ] Actual/360 [ ] 30/36092 Accrual period: [From] __ / [To] __ / Days ____93 Per diem: $ ________94 Pre-petition interest: $ ________95963) Other Charges (only if supported)97 Late fees: $ ________98 NSF/other fees: $ ________99 Attorney fees (pre-petition): $ ________100 Other allowed charges: $ ________101 Charges total: $ ________1021034) Claim Summary104 Principal: $ ________105 Pre-petition interest: $ ________106 Other charges: $ ________107 TOTAL CLAIM AT PETITION: $ ________108109Documentation: [ ] Rate clause [ ] Payment ledger110[ ] Day-count rationale [ ] Charge authorization [ ] Signature/date111```112113## Validation Checklist114115Run before filing:116117| Error | Fix |118|---|---|119| Wrong principal baseline | Reconcile to balance after last credited payment |120| Wrong day-count basis | Use contract or documented basis |121| Wrong compounding method | Match contract; default to simple interest |122| Unauthorized fees included | Remove; note authority required |123| Missing rate source | Document statute, contract clause, or judgment paragraph |124| Interest calculated past petition date | Cap unsecured/general claims at petition date |125126## Pitfalls127128- Convert percentages to decimals only inside formulas; preserve units elsewhere.129- Never mix post-petition accrual into pre-petition totals.130- Federal post-judgment rate (§1961) is a fallback, not default for non-judgment debt.131- State prejudgment rates vary by jurisdiction and date — verify current statute before relying.132- Flag uncertain statutory questions (e.g., solvent-debtor treatment) with [VERIFY] and venue-specific authority.133134## Cross-References135136- `@bankruptcy-proof-of-claim`137- `@bankruptcy-collateral-valuation-reference`138- `@bankruptcy-objection-to-proof-of-claim`139- `@commercial-loan-analysis`140141## Key Statutes142143- 11 U.S.C. §502(b)(2) — unmatured interest144- 11 U.S.C. §506(b) — post-petition interest (oversecured)145- 28 U.S.C. §1961 — post-judgment interest146- Applicable state prejudgment interest statute (verify per jurisdiction)147148---149150**Key changes made:**151152- **Frontmatter**: Tightened description to lead with what it does and include clear trigger guidance in third person153- **Structure**: Added Quick Start section for rapid orientation; reorganized from numbered "Output Structure / Process" subsections into named semantic sections154- **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 list155- **Worksheet**: Streamlined — removed decorative separator lines, compressed the documentation checklist to a single line156- **References → Key Statutes**: Renamed for clarity and brevity157- **All domain accuracy preserved**: Rate priority hierarchy, §506(b) rules, charge gate logic, validation checklist, and [VERIFY] flags are intact
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