GDP Calculation? Hidden categories: All articles with unsourced statements Articles with unsourced statements from April All stub articles. Louis, MO The formula for calculating net investment is:. Capital Consumption Allowance CCA Capital consumption allowance CCA is the amount of money a country has to spend each year to maintain its present level of economic production. While this may not be a problem for a year or two, a net investment that is negative for a prolonged time period will render the enterprise uncompetitive at some point.