Why is the lottery lump sum less than the advertised prize? Money paid later is worth less than money paid now, and the headline adds up every future instalment at face value. The difference between an annuity and a lump sum is therefore mostly timing. The annuity spreads payments over many years, often rising each year to keep pace with prices, while the lump sum hands over the whole present value at once and leaves its growth in the winner's hands.
A lump sum in the lottery is the cash value of the jackpot: the money the organiser would need today to fund the annuity it advertises. How is a lottery lump sum calculated? The organiser prices the stream of future payments at current interest rates and pays that present value instead. When rates are high, the lump sum is a smaller share of the headline; when they fall, the share grows. What percentage it comes to therefore moves from draw to draw, often between half and two thirds.
Should a winner take the lump sum or the annuity? No single answer suits everyone. People who decide between the two usually weigh a few things: whether they trust themselves with a large balance, whether they could invest it at a better return than the annuity implies, how old they are, and whether a steady yearly income would protect them from spending too fast. Advisers often suggest settling the choice before claiming, since it is not always reversible.