We spent 40 hours a month manually generating invoices. Our CFO said we were losing money.

We bootstrapped our SaaS to $30k MRR with a very simple pricing model. But last year, we started landing larger mid-market clients. These clients all had one thing in common: they refused to use our automated Stripe checkout. They demanded to be billed via custom invoices, with net-30 terms, purchase order (PO) numbers, and specific line items for their procurement departments.

Because we desperately wanted the revenue, we said yes to every custom billing request. We didn't want to spend engineering time building an enterprise billing system, so my co-founder and I just did it manually.

I finally tracked our time last month. We spent 40 hours (an entire work week) manually generating PDFs, chasing down PO numbers, emailing finance departments, and reconciling payments. We were acting as our own collections agency.

Our CFO (who is our part-time advisor) looked at the numbers and pointed out something terrifying: If we factored in the opportunity cost of the engineering hours we weren't shipping, and the delayed cash flow from net-30 terms, we were actually losing money on those enterprise deals. We were so focused on the top-line revenue that we ignored the massive operational drag.

Now we have to pause our product roadmap to build a custom billing engine that integrates with their procurement software, just so we can stop doing manual data entry.

For founders who have moved upmarket: How did you transition from simple Stripe checkouts to enterprise billing (invoices, POs, net-30)?

Did you use a third-party tool (like Chargebee or Stipe Invoicing), or did you build it in-house? And how did you handle the delayed cash flow while waiting for these big checks to clear?