As a single woman with no children, Karen Callahan is putting together the financial pieces that will protect her for a potentially long life on her own. A large piece of her puzzle: getting as much Social Security income as she can.Ms. Callahan, 67, of Marlborough, Mass., is holding off on claiming her benefits until she turns 70, when she will be eligible for $3,100 a month. If she claimed today, she said, her benefit would be permanently reduced to about $2,500.The income from a web design business she owns will cover her expenses until 70, including a $375 monthly condo fee on her …
