What is Withholding tax and dividend enhancement?

A withholding tax is a tax deducted at source from dividends paid to a non-resident holder, at a statutory rate that a tax treaty may reduce. Dividend enhancement is any arrangement in which the exposure is held, over the dividend date, by the party with the lowest tax cost, who passes part of the saving to the economic holder, typically through the share $\eta$ of the dividend paid in a swap.