Cash Flow Analysis — Annual or Monthly?

A reader of one of my books wrote to me recently with a very worthwhile question.  When we build a pro-forma analysis of future cash flows from a real estate investment, why do we annualize those cash flows instead dealing with them on a monthly basis?  After all, rent is typically collected and bills paid monthly.

The quick and facile answer, of course, is because we’ve always done it that way. Back in the day, we didn’t have powerful personal computers and sophisticated real estate software, so one might argue that this annual approach is just a holdover from a golden age that has passed us by.

Then again, there may be some wisdom inherent in this approach. To make monthly estimates of future cash flows requires monthly, rather than annual, estimates of income, expenses and debt service. The task is not impossible, but collecting, organizing, and deploying this amount of data will surely take much greater time and effort, presumably up to twelve times as much. And we all know that time is money.

Is it practical to do this, and if so, is it worth the effort?  It’s important to keep in mind that you’re not performing an accounting function but rather making projections about what’s going to happen in the future. It’s often difficult enough to estimate your annual cost for heating fuel or electricity five years hence. Trying to estimate such costs by the month can be even more problematic and time-consuming.

Assuming that someone else hasn’t already closed on this property while you were playing Hamlet, did you in fact gain any additional insight or advantage as a reward for your extra effort?

A monthly projection of future cash flows substantially increases your “degrees of freedom” in making estimates, so the monthly estimates are not only more difficult to make, but they also provide you with many more opportunities to be wrong. To put it another way, you are just as likely to introduce errors in timing as you are to add precision, thus offsetting at least some if not all of the benefit of your considerable extra effort.

Having said all this, it is also true that a dramatic skewing of cash flow toward the beginning of a year could make a noticeable difference in a particular discounted cash flow calculation. One might feel that is justified to handle such an atypical income stream differently.

For what it’s worth, my opinion is that the conventional wisdom here actually makes sense. Forecasting the future is an imperfect art; in most situations, annualizing the net cash flow is a reasonable compromise with reality and a task of more manageable proportions.

Frank Gallinelli


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