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On September 29th, former employees of 3M must decide whether to take a lump-sum payout on their pension or take a monthly pension check in the future. The decision should not be taken lightly. Depending on which way the market winds blow and what assumptions you use, this could be a $1 million decision. Like most financial decisions, there is no clear cut answer. What's best for you may be different than what is best for your neighbor. Both decisions involve some assumptions and even a certain amount of risk. To determine if your company is making you a reasonable offer, you will need know what your monthly pension is worth in today's dollars....

With the exception of your fixed pension amount, the other two variables require some assumptions. No one knows how long they will live, but you can get an idea of how long the government thinks you might live on the social security website.

Interest rates are anyone's guess, but since a pension is guaranteed you might want to start with a return equal to that of the 30-year US Treasury bond. According to the U.S. Treasury, a 30-year bond pays about 3.2%.