If you've been to London and taken the Underground, you're probably familiar with the phrase, "Mind the gap." It's a recorded warning to train passengers to be cautious when crossing the gap between the train door and the station platform. Having an affinity for the British and their sense of humor, this resonated with me and puts a smile on my face whenever I think of it.
When planning for retirement, you also need to "Mind the gap." Just like with the Underground where you have an unsafe opening between the station platform and the train door, there's often a separation between retirement expenses and income, with income not being sufficient to match expenses in a particular year. I like to refer to this as a "net expense year."