Net Return Index Variants and Withholding Tax

When an index reinvests dividends, it has to decide how much of the dividend actually gets reinvested. A "gross" or plain total-return index assumes every dollar of dividend is reinvested in full, as if no tax were ever taken out. A "net return" index is more realistic for a real investor: it assumes withholding tax is deducted from foreign dividends before reinvestment, exactly as would happen to an actual international fund, so only the after-tax amount compounds back into the index.

Withholding tax is charged by the company's home country on dividends paid to foreign holders, and the rate depends on both the paying country and the investor's country, often set by tax treaties. Because the exact rate an individual investor pays can vary by domicile, index providers publish net-return variants using a standardized assumed rate (commonly the rate applicable to a particular category of institutional investor) rather than trying to model every investor's actual tax situation.

The practical effect: over long periods, a net-return index will show a noticeably lower cumulative return than the equivalent gross total-return index on the same stocks, purely because less money was reinvested at each dividend date. This matters directly for performance measurement — a fund that holds foreign dividend-paying stocks and actually pays withholding tax should be benchmarked against a net-return index, not a gross one, or it will look worse than it really is simply from an apples-to-oranges comparison.