Inside Tonga’s Central Bank Reforms to Modernise Monetary Policy and Manage Liquidity

The IMF’s report shows how Tonga’s central bank is quietly modernising its monetary policy by introducing a policy rate, improving liquidity management, and moving from administrative controls toward market-based tools. These reforms aim to strengthen monetary transmission and protect the exchange rate peg in an increasingly volatile global environment.

Far from the world’s major financial centres, the National Reserve Bank of Tonga is undertaking a careful but consequential overhaul of how it manages money. Guided by technical support from the International Monetary Fund’s Monetary and Capital Markets Department, the reform effort aims to modernise the country’s monetary policy without destabilising the exchange rate peg that has long anchored economic stability. The IMF’s technical assistance report captures this transition at a critical moment, as Tonga adapts its institutions to a more uncertain global financial environment.

From Administrative Controls to Market Signals

For years, Tonga’s monetary system relied more on controls than on markets. The pa’anga was pegged to a basket of foreign currencies, capital controls limited financial flows, and inflation remained broadly contained. But behind that stability lay structural weaknesses. Interest rates played little role in guiding economic decisions, excess liquidity accumulated in the banking system, and the interbank market barely functioned. As donor inflows and foreign exchange reserves grew, the central bank lacked the tools to absorb surplus liquidity or steer short-term interest rates effectively.

Recognising these gaps, the IMF began working with the central bank in early 2025 to design a more modern operational framework. Since then, Tonga has introduced an interest rate corridor, clarified standing lending and deposit facilities, activated collateral rules, and resumed open market operations through the issuance of central bank notes. These reforms mark a shift toward using prices, rather than directives, to influence financial conditions.

Why the Policy Rate Matters

One of the most visible changes has been the introduction of a formal policy rate, initially set at 2 percent. This rate now serves as a benchmark for central bank operations and a signal to the financial system. But the IMF report makes clear that announcing a policy rate is only the first step. What matters more is how that rate is determined and whether it supports the exchange rate peg.

In a pegged system like Tonga’s, interest rates must broadly align with those in anchor countries such as the United States, Australia, New Zealand, and Fiji. The IMF therefore recommends using an “uncovered interest parity” approach, which links Tonga’s policy rate to a weighted average of foreign rates, adjusted for country-specific risk. Current calculations suggest that Tonga’s rate may eventually need to rise. The report stresses, however, that this adjustment should be gradual, predictable, and carefully communicated to avoid economic shocks.

Liquidity: The Hidden Engine of Monetary Policy

While the policy rate attracts attention, the report highlights liquidity management as the real engine of effective monetary policy. Excess liquidity, money sitting idle in the banking system, has weakened interest rate transmission and discouraged banks from trading with one another. The central bank’s existing liquidity forecasts, produced monthly and often inaccurately, have not been sufficient to guide operations.

To address this, the IMF helped institutionalise a detailed liquidity forecasting framework that models cash in circulation, foreign asset movements, and government account balances. The analysis reveals clear seasonal patterns in cash demand and foreign inflows, but also exposes serious data gaps, especially in tracking government transactions. Without reliable daily data, even advanced forecasting models struggle to deliver accurate results.

Building Institutions, Not Just Models

The IMF’s central message is that technical tools must be backed by strong institutions. The report recommends creating a dedicated Liquidity Forecasting Unit, supported by a comprehensive daily database and stronger coordination with the Ministry of Finance. Over time, liquidity forecasts should be published, helping banks anticipate central bank actions and supporting the development of an interbank market.

Progress so far has been encouraging. Most near-term reforms recommended earlier in 2025 have been implemented, and others are underway. Still, challenges remain, including unfinished work on emergency liquidity assistance and delays in setting up a Treasury Single Account. These issues, the IMF argues, are not side details but core elements of a modern monetary system.

A Careful Path Forward

The report concludes on a cautiously optimistic note. Tonga is not abandoning its exchange rate peg, nor rushing toward financial liberalisation. Instead, it is building the operational capacity needed to defend stability in a more market-driven way. For a small island economy exposed to global shocks, that balance between reform and caution may be its greatest strength.