Taiwan's economy ranked as the 22nd largest in the world last year with a GDP totaling US$355.7 billion, tallies published in April by the IMF showed.
The same figures showed that Taiwan was the world's 20th largest economy in 2004, with a GDP totaling US$322.3 billion, but was surpassed by Turkey in 2005, to fall to 21st place with a GDP of US$346.7 billion.
Taiwan was also surpassed last year, this time by Indonesia, dropping the nation back another notch.
However, the Directorate General of Budget, Accounting and Statistics ranked Taiwan 21st in the world last year with a GDP of US$364.2 billion.
The use of different measurement tools and models could account for the different figures given for Taiwan's economy, experts said.
One local financial analyst said the difference between the estimates given by the IMF and the government could be the result of a weaker NT dollar and the use of different NT dollar/US dollar conversion rates.
To boost exports and therefore economic growth, the government tends to keep the NT dollar relatively weaker than the currencies of its trade competitors.
The IMF forecast that Taiwan would retain its GDP ranking this year, remaining the world's 22nd largest economy with an estimated GDP of US$365.3 billion.
The US was the world's largest economy last year, with a GDP totaling US$13.24 trillion, followed by Japan at US$4.37 trillion, Germany with US$2.89 trillion and China with a GDP of US$2.63 trillion, the IMF said.