September COFIX Hits 3.43%: A Guide for Foreigners with Korean Loans
Quick answer: The Korea Federation of Banks published the September COFIX on October 15 at 15:00 KST. The new-funds figure is 3.43%, up 0.25 percentage points from August’s 3.18% – the largest monthly jump in about three years and ten months. The outstanding-balance COFIX is 3.15%, and the new outstanding-balance COFIX is 2.79%. Korean banks usually apply the new figure to new variable-rate mortgages from the next day (October 16). Existing loans change only on their contracted reset date. The Bank of Korea (BOK) still decides its base rate on October 22 (currently 3.00%). (Korean readers: 9월 코픽스 3.43% 공시.)
What COFIX is
COFIX (Cost of Funds Index) is the main benchmark for many Korean variable-rate home loans. The KFB publishes it from data supplied by major banks.
- COFIX on new funds (신규취급액 기준): reflects only money banks raised that month, so it follows market rates quickly. September: 3.43% (August: 3.18%).
- COFIX on outstanding balance (잔액 기준): includes older funding too, so it moves more slowly. September: 3.15% (August: 3.05%).
- New COFIX on outstanding balance (신잔액 기준): also includes settlement deposits. September: 2.79% (August: 2.71%).
- Short-term COFIX: published weekly. It reached 3.43% on October 14 (week of Oct 3–9).
The weekly short-term index and the monthly index are calculated on different bases, even when the printed rate matches.
Key dates this month
| Date (KST) | Event | Why it matters |
|---|---|---|
| Oct 14 | Short-term COFIX 3.43% | Funding-cost signal |
| Oct 15, 15:00 | September monthly COFIX | New-funds 3.43%; outstanding 3.15%; new-outstanding 2.79% |
| Oct 16 (typical) | Banks apply new COFIX to new variable loans | Check offer letters and bank rate boards |
| Oct 22 | BOK Monetary Policy Board | Base rate now 3.00% |
Sources: KFB COFIX (English), Money Today.
Who is affected
- New variable-rate borrowers: banks usually reprice from the day after publication. For reference only (dated figures after the August COFIX): KB Kookmin 4.35–5.75% and Woori 4.80–6.00% on new-COFIX-linked products, as reported by CBC News on September 16, 2026. Those ranges will change after today’s figure (CBC News).
- Existing borrowers: your rate changes only when your contract’s reset cycle (often 6 or 12 months) arrives. Check the rate type and next reset date in the bank app or loan contract.
This article is information only, not lending or investment advice. Actual rates depend on the bank and your credit profile.
FAQ
Does a higher COFIX raise my payment tomorrow?
Usually not for an existing loan. New loans often see the new COFIX from the next business day; existing loans wait for their reset date.
Is the short-term 3.43% the same as the September monthly 3.43%?
The numbers match this week, but the calculation bases differ. Treat them as related signals, not identical indexes.
What will the BOK do on October 22?
Major bank forecasts published on October 14 leaned toward a hold this month, with possible hikes later. Those are forecasts, not decisions.
Where can I check the official number?
The KFB publishes COFIX in English.
Sources
- Korea Federation of Banks, COFIX announcement Oct 15, 2026 (September figures), https://m.kfb.or.kr/eng/cofix/cofix.php (checked Oct 15, 2026)
- Money Today, Oct 15, 2026, COFIX +0.25pp (largest jump in 3 years 10 months), https://www.mt.co.kr/finance/2026/10/15/2026101514414539694 (checked Oct 15, 2026)
- CBC News, Sep 16, 2026, KB/Woori rate ranges after August COFIX, https://www.cbci.co.kr/news/articleView.html?idxno=607033 (checked Oct 14, 2026)
