It’s 35%, considering JUST the federal taxes (yes, state taxes push that up quite a bit, and if I were you I’d move to a cheaper state before getting your pay off). Meaning you’d take home a lump sum of $325,000 (assuming you don’t pump part of that into school expenses, mortgage interest, gifts to charity, medical expenses up to a point, expenses for starting a home business, IRAs, 401ks, 503cs, and other little tax shelters which would give you more loot down the road while increasing your “worth”). The tax bracket for a married person making less than $100,000 is more like 25%, again considering all that other crap is ignored.
The difference is $325,000 now, versus $750,000 over the next 20 years. A little over 230% better.
Of course, there are reasons to take the lump sum. A good one would be investing in a new sole proprietership. You could use that full $500,000 to purchase a TON of great equipment and basically take a loss the first year…and pay little tax (basically, only on the amount you DON’T invest in the business, AFAIK). Then, you use your equipment to start making money the following year. Make sure you get a good accountant! There are some forms of business that do this consistantly and as such pay hardly any tax – mostly R&D firms.
Another reason to take the lump sum would be if you planned on leaving the country without paying tax on it. There are some fine nations with low costs of living and no extradition treaties with the US. You could live like a king in such a nation. You COULD be a king in such a nation!
And finally, if you’re over 60 years old, take the lump sum. Most lotteries won’t give your kids the balance.
Here is a record of my lottery expenditures since Jan 1, 1996 (from my Quicken data file):