課税所得・跳ね上がる

Extract from an article about individual and corporate income tax:

個人の場合、課税所得が年間900万以下だと所得税率は23%ですが、900万円を1円でも超えるといきなり税率は33％に跳ね上がります。

For individuals, if taxable income is 9 million yen or less per year the income tax rate is 23%, but if it exceeds 9 million yen by even 1 yen, the rate suddenly jumps to 33%.