I frequently get asked “How do I build my budget for marketing if I’m practicing Agile Marketing? Finance is asking me for an annual budget; how do I give them numbers if I don’t know what I’m doing beyond the next one or two sprints?”

One answer is to throw out year in advance budgets, just like you toss out yearly marketing plans. Too much can change, and a yearly budget for most businesses is an approximation, and often not very accurate. However, I realize that this option may not always be available, so I have a different suggestion.

Base your budget not on marketing activities, but by understanding the average lifetime value of a customer, as well as the average cost of acquisition of that customer, and marketing’s portion of that cost of acquisition. So if the CEO forecasts a certain revenue number for the year, break that number up into revenue from existing customers and revenue from new customers. Determine how much you need to spend, on average, marketing to existing customers (getting them to buy new products, upselling, etc) and know this number per customer. For example, if the revenue goal from new customers is \$10 million, and the average revenue per existing customer is \$100 per year, and you need to spend \$5 per customer per year marketing to these existing customers, then your budget for this portion of your marketing is \$500,000 (\$10M divided by \$100 times \$5).

For acquisition of new customers, you should apply similar math. If the goal is to acquire 50,000 new customers in the coming year, and the average lifetime value of a customer is \$500, and the marketing costs associated with acquiring that customer are 15% of the average lifetime value, or \$75, then your budget for acquiring new customers for the coming year is \$3,750,000.

Note that this model takes into account whether a business is mature, where most of the revenue comes from existing customers, or in growth mode, where acquisition of new customers is the primary focus.

Understanding your marketing costs in this way has a host of benefits. First, it focuses you on the right goals: acquiring new customers and the revenue that they bring with them. Second, if the goals change during the year, as they frequently do, it’s much easier to have a conversation about changes to the budget. For example, if the revenue budget is increased by 25%, primarily by bringing in new customers, then you should be able to calculate the marketing costs of bringing in those new customers. If the CEO says that he wants to increase the revenue budget with no corresponding increase in marketing, then the cost of acquisition would have to come down, and probably severely. That may or may not be realistic. But rather than make the conversation about whether you should participate in this trade show or run these ads, you can have the conversation around cost of acquisition, something the CEO and finance people are much more likely to understand.