Credit Over Debt balance-transfer funding-budget benchmark v1 — 15 October 2026

Not a card recommendation, market census, lender quote or complete revolving-credit simulation. Four issuers selected for a transparent comparison of fee and timing; no affiliate links or paid inclusion. Public pages and linked summary boxes were reopened on 15 October. Older document dates are not announcements today.

Inputs: inputs.json (full evidence, exclusions, rates, timing, limitations); inputs.csv (numeric extraction). Results: results.csv. All monetary fields are integer pence. Use method.mjs with benchmark({principalPence:300000,feeBasisPoints:349,minimumFeePence:0,months:38}). Standard JavaScript; no dependencies, tracking or network calls.

Fee=max(minimum fee, percentage of principal rounded half-up to a penny). Monthly principal target=ceil(principal/months) pence; final target=remaining principal. First-month funding budget=principal target+fee reserved separately at outset. Total budget=principal+fee. Fee is NOT presumed to share a promotional interest rate. The reserve is a budgeting convention, not a payment-allocation instruction. Check when/how your actual fee is paid and whether interest accrues. These outputs exclude any such interest.

Scenarios assume immediate transfer and the advertised maximum period. Substitute the actual offered period and exact end date. Account-opening versus transfer-date clocks differ. No new transactions, defaults, minimum-payment or post-promo simulations; contractual payments may be higher. Six-month comparisons use the same horizon, unlike maximum-period comparisons. A delay, shorter offer, fee treatment or residual balance requires a fresh real-cost calculation. No saving versus staying with an old card is estimated.

Recalculation: separate Python Decimal penny arithmetic independently reproduced 12 cases including minimum fee, half-penny rounding and one-penny payoff. JavaScript regression tests compare the exact outputs. Separate automated Codex roles, same operator; not independent human audit.

Primary explanations: https://www.moneyhelper.org.uk/en/everyday-money/credit/deciding-whether-to-transfer-your-credit-card-balance and https://www.hsbc.co.uk/credit-cards/what-is-a-balance-transfer/ (both retrieved 15 October). Individual issuer evidence is in inputs.json.

Attribution optional. No required link or anchor. Facts may change; check current issuer documents before use. Errors: use Credit Over Debt's corrections page. Repository publication alone is not verified public serving.