The difference between your annual income needed and your retirement income streams is your gap, and that’s what needs to be solved with your savings and investments, including real estate. Retirement income is usually defined by Social Security and pensions. You may have a handle on current expenses, but many expenses change in retirement, like health care, long term care, travel, etc. The gap between income and expenses may give us an idea of the annual income needed in retirement. The gap gives your personal financial plan a clear objective for your investment portfolio, which may also include real estate.