Model a fixed monthly debt budget with nominal interest rates. Compare avalanche and snowball, remaining debt and interest, and export an illustrative roadmap.
Monthly interest equals the opening balance × nominal annual rate / 1200, followed by payments. Initial minimums plus extra form a fixed budget; freed minimums roll into other debts. Minimums are capped at each balance, then the remainder follows the selected strategy. Rates and minimums stay fixed. No fees, new borrowing, daily accrual or lender cent-rounding are modeled. The first payment is in the next calendar month; dates are illustrative. The no-extra baseline also rolls minimums over.
Payoff and interest comparisons are available only when the corresponding plans complete. Incomplete plans show their modeled months, partial payments and interest, and remaining balance. Numerical work or representability limits may leave individual fields unavailable; no debt is forgiven to make the model finish.
CFPB: https://files.consumerfinance.gov/f/documents/cfpb_your-money-your-goals_debt-action-plan_tool_2018-11.pdf