Final answer:
The distribution treated as a dividend in 20X3 would be $100,000.
Step-by-step explanation:
In 20X3, the distribution treated as a dividend would be $100,000
Earnings and profits (E&P) are used to determine the taxable dividend amount. If the distribution exceeds the accumulated E&P, it is considered a dividend to the extent of accumulated E&P, and any excess is treated as a return of capital or capital gain. In this case, since the accumulated E&P is $100,000 and the distribution is $300,000, $100,000 of the distribution is treated as a dividend in 20X3.