"If your business is doing well, or you sell property or whatever it is — set 30 percent aside of the gross amount of the proceeds," he says.
Put the cash in something liquid like a money market account, says Losi, so that you can easily take it out when you need to pay taxes, but you don't have to worry about it decreasing in value.
"If you do that, you'll never be surprised," he says.
Spending the entirety of your windfall or reinvesting it in something risky can leave you in a lurch come tax time.
"If you don't [put 30 percent aside] and you spend on personal [items] like a house or a car, or if you put it in securities, you've really got only yourself to blame," Losi adds.