A working paper from the London School of Economics found that tax cuts for the rich across 18 OECD countries over the past 50 years increased their share of pre-tax national income but did not affect economic performance or unemployment rate:

"Our results show that…major tax cuts for the rich increase the top 1% share of pre-tax national income in the years following the reform. The magnitude of the effect is sizeable; on average, each major reform leads to a rise in top 1% share of pre-tax national national income of 0.8 percentage points. The results also show that economic performance, as measured by real GDP per capita and the unemployment rate, is not significantly affected by major tax cuts for the rich."The estimated effects for these variables are statistically indistinguishable from zero.”

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