By late 1948, most of the KMT’s expenditures at that point were funded by confiscating goods from public and private sectors in Taiwan. After the KMT lost the Huaihai campaign, early 1949, things got worse. Since Taiwan was also reeling from the aftermath of WW2, and KMT’s massacre of Taiwanese elites, all that plundering soon also tanked Taiwan’s economy beyond the ability to support KMT’s war efforts. That accelerated the the process of KMT printing the Gold Yuan into wallpaper by April 1949.
However, load of people with ties to the KMT still was hoarding a large amount of Gold Yuan, and the KMT desperately needed a way to turn those into something with value again. The way to do it was to create the NTD in June of 1949. Forcing the exchange rate between OTD and NTD to 1 to 40K basically reduced the wealth of those holding OTD by 555 times, and allowed the KMT and those with ties to KMT to turn junk into real money instantly.
The table below would give you an idea of what’s happening:
YEN: Japanese Yen
TYN: Taiwan Ginkoken, a.k.a Taiwanese Yen
FB: Fabi, the original paper note in ROC
OTD: Old Taiwan Dollar, released in May 1946
GY: Gold Yuan, the replacement to Fabi in August 1948
NTD: New Taiwan Dollar, replacement to Old Taiwan Dollar in June 1949
SY: Silver Yuan, the replacement to Gold Yuan in July 1949