Where did you see it is forfeited?
You have to report the carryover every year until it's used up. You can't skip a year. Even if you don't report it on your return you have to reduce it by the 3,000 (1,500 MFS) when you carry it over to next year. You can't choose when to use it.
This is from the IRS Pub 550 page 66 last column....
"When you figure the amount of any capital loss carryover to the next year, you must take the current year's allowable deduction into account, whether or not you claimed it and whether or not you filed a return for the current year. "
Here is pub 550… http://www.irs.gov/pub/irs-pdf/p550.pdf
You might want to amend the last 3 years to include it. But If you have a negative AGI or negative taxable income it will show up on 1040 BUT it won't reduce the carryover to the next year. So if you didn't have any taxable income you can carryover the full amount.
