How do negative interest rate policies work in practice, and what is the 'reversal rate' that limits how negative rates can go?

Question

AcadiFi · Accepted Answer

Negative interest rate policy (NIRP) charges commercial banks for holding excess reserves at the central bank, creating an incentive to lend or invest those reserves rather than park them. In practice, implementation requires a tiered reserve system to prevent bank profitability from collapsing. **Mechanical Implementation** Most central banks using NIRP apply a tiered system — only reserves above a threshold are charged the negative rate. This protects bank net interest margins on the majority of their reserve holdings. **Worked Example — Kensington Central Bank Tiered System:** Kensington Central Bank sets a policy rate of -0.50%. Commercial banks hold total reserves of $850 billion. | Reserve Tier | Amount | Rate Applied | Annual Interest | |---|---|---|---| | Tier 1: Required reserves | $200B | 0.00% | $0 | | Tier 2: Exempt excess (6x required) | $600B | 0.00% | $0 | | Tier 3: Marginal excess | $50B | -0.50% | -$250M (charge) | | **Total reserves** | **$850B** | **Effective: -0.015%** | **-$250M** | Only $50 billion (5.9% of total reserves) is actually charged at the negative rate, but the marginal incentive affects pricing on all new lending. **The Reversal Rate Concept:** The reversal rate is the interest rate level below which further rate cuts become contractionary because they destroy bank profitability to the point where lending contracts rather than expands. \`\`\`mermaid flowchart TD A["Rate Cut Below Zero"] --> B{"Above
Reversal Rate?"} B -->|"Yes"| C["Banks Lend More
to Avoid Charges"] C --> D["Expansionary:
Credit Growth"] B -->|"No"| E["Bank Margins
Crushed"] E --> F["Banks Tighten
Lending Standards"] F --> G["Contractionary:
Credit Contraction"] A --> H["Depositors Move
to Cash?"] H --> I{"Practical Storage
Cost > Negative Rate?"} I -->|"Yes"| J["Deposits Stay
in Banking System"] I -->|"No"| K["Cash Hoarding
Policy Ineffective"] \`\`\` **Empirical Observations from NIRP Economies:** 1. **Deposit rate floor** — most banks have not passed negative rates through to retail depositors (below roughly -0.50%), creating a squeeze on net interest margins. 2. **Lending response is mixed** — corporate lending increased modestly in the eurozone, but mortgage lending in some countries was already strong and did not accelerate further. 3. **Currency depreciation** — NIRP's strongest channel may be exchange rate depreciation rather than domestic credit stimulation. 4. **Cash hoarding is minimal** — the cost of storing, insuring, and transporting large amounts of physical cash generally exceeds the negative rate, keeping deposits in the system. 5. **Estimated reversal rates** — researchers estimate the reversal rate at approximately -1.0% to -1.5% for most banking systems, depending on bank profitability, capital adequacy, and competitive dynamics. For CFA Level II, the critical insight is that NIRP has an effective lower bound determined by bank profitability, not just cash storage costs. Check our CFA Level II Economics course for monetary policy edge cases.

How do negative interest rate policies work in practice, and what is the 'reversal rate' that limits how negative rates can go?

Master Level II with our CFA Course

Related Questions

Practice Questions