Box 8 on 1099-DIV

You don't enter it directly on 1040. You enter it as an adjustment to the cost of the stock on your Schedule D in the current or some future year.

Liquidation distributions reduce your basis (cost) in the corporation's stock. Then, if and when you sell your stock, or the liquidated corporation cancels the stock, or the distribution exceeds your original basis, you have either a capital gain or loss, depending on the difference between the liquidation distribution(s) and your original basis (greater or less than zero).

It gets more complicated if you made multiple purchases of the stock...the distributions have to be allocated.

-Mark Bole