interest-calculation-reference

name	interest-calculation-reference
title	Bankruptcy Interest Calculation Reference
description	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.
author	CaseMark
author_url	https://github.com/CaseMark/skills/tree/main/skills/legal/interest-calculation-reference
license	Apache-2.0
version	0.1.0
execution_mode	open
jurisdiction	us
practice	bankruptcy
language	en
tags	["analysis","checklist","litigation"]

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

1. Collect core inputs (principal, rate, dates, day-count basis).
2. Determine rate source using priority hierarchy.
3. Calculate pre-petition interest using the formula.
4. Apply charge inclusion gate to fees.
5. 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-Basis
• Total 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