Is my cost per customer going up?
You are spending more on marketing than you did a year ago. But are you getting more customers, or just paying more for the same number? Here's how to tell.
The short answer
Is your cost per customer rising? Calculate your CAC (total marketing and sales spend / new customers) for each of the last 6 months. If the number is climbing while customer volume is flat, you are paying more for each customer and your acquisition is getting less efficient.
Rising CAC is a silent margin killer
Your cost per customer went from $480 to $680 over the last year. That is a 42% increase. If you acquired 20 customers per month, your marketing spend jumped from $9,600 to $13,600 monthly. That is an extra $4,000 per month that comes directly out of your profit.
The problem is insidious because revenue might still be growing. You see the top line going up and assume everything is fine. But the cost to generate that revenue is growing faster, and your margins are quietly eroding.
CAC rises for many reasons: ad platform costs increase, your market gets more competitive, your messaging gets stale, or you are saturating your best audience. The first step to fixing it is knowing it is happening.
What drives your cost per customer up or down
- Ad platform cost inflation. Google and Meta auction-based pricing means costs rise as more competitors bid on the same keywords and audiences. Your campaigns can perform identically and still cost more year over year.
- Audience saturation. You have already reached your best prospects. Expanding to new audiences costs more because they are less qualified.
- Channel mix shift. If you moved spend from a low-CAC channel (referrals, organic) to a high-CAC channel (paid ads), your blended CAC rises even if each channel is performing the same.
How to calculate CAC trends from QuickBooks and your CRM
- 1Pull 6 months of marketing spend from your P&L
In QuickBooks or Xero, run a Profit and Loss for the last 6 months with monthly columns. Note the advertising and marketing expense lines for each month.
- 2Count new customers for each month
From your CRM or invoicing system, count first-time paying customers for each month. In QuickBooks, use the Sales by Customer Summary and identify new names month by month.
- 3Calculate CAC for each month
Marketing spend / new customers = CAC. Do this for all 6 months. Plot the numbers. Is the trend going up, down, or flat?
- 4Compare CAC growth to revenue growth
If CAC is rising 5% per month but revenue per customer is also rising 5%, you are treading water. If CAC is rising faster than revenue per customer, you are losing ground.
Total time: 20-30 minutes per month. The customer count identification is the most manual part, especially without a CRM.
What makes CAC tracking hard to maintain
- New customer identification is manual. Unless your CRM clearly tags first purchases, you are scrolling through invoices each month to figure out who is new.
- Spend categories are inconsistent.Some marketing spend is categorized as “Advertising,” some as “Marketing,” some as “Consulting.” You need to be consistent each month or the trend is meaningless.
Or monitor your cost per customer automatically every month
Bottomline connects to your accounting software, CRM, and ad platforms. It calculates your true CAC each month by matching spend to actual paying customers:
Bottomline does not rely on ad platform self-reporting. It matches actual money spent (from your accounting software) to actual new customers (from your CRM and payment data) to give you a CAC number you can trust.