Every decision a company makes is a financial decision. So finance isn't just the function that reports on the business; it's where the business gets decided.

Which makes it worth asking where your finance team's hours actually go. Reconciling last month. Chasing receipts. Policing a $30 subscription. All of it backward-looking.

That's why I use Brex: corporate cards plus AI-native workflows that absorb the record-keeping. Zero-touch receipt matching, real-time policy enforcement, continuous reconciliation. Controls fire before money leaves the account. Close takes days, not weeks.

Defense handled. Go play offense. Thousands of companies — including Anthropic, Coinbase, and DoorDash — already run on Brex. Head to brex.com/metrics to join them.

👋 Hi, it's CJ Gustafson and welcome to Mostly Metrics - my newsletter for CFOs about the metrics and financial strategies behind the world's best businesses.

And today I’m an author!

When it comes to budgeting, I've long thought there are no new ideas, merely new ways to repackage them (or to repackage your budget). I've written more than 25 posts on the subject of annual planning, or more than 80,000 words (roughly the length of a Harry Potter novel). In doing so, I shook out the couch cushions on every possible topic that annual planning can cover… zero based budgeting, hybrid zero based budgeting, monthly reforecasting, headcount approvals, and running interlock meetings with department heads that don't result in bloodshed.

Underneath all 80,000 of those words is the same core idea, one that I've hammered ad nauseum at any place I've been employed: at a startup the scarcest resource isn't money, it's mental bandwidth, and planning is how a company forces everyone to spend that bandwidth on the same stuff at the same time. It gives you an evolving baseline to course-correct against as the year changes on you.

With the advent of AI we finally have a "new" way to plan, not merely a revised way to talk about it (although I have proven good at that). At a time when people are losing their minds over tokens, and attempting to find some measure of ROI to cling to, we're also embarking on a world of continuous forecasting derived from a foundation of disparate data sources… something that was never possible before. It's scary, and it's beautiful.

Since this is my full-time job, I have the benefit of speaking to hundreds of finance leaders each year. I've done exactly 104 interviews since the first Annual Planning Bible was published. What follows is a revision to the first, layering in what I've learned in the last 365 days about how AI, probabilistic forecasting, and token consumption impact the P&L.

For the first time in a long time, Finance feels like they don't have the answers. The adult in the room (lol) doesn't totally know who moved their cheese. If that feeling resonates with you, you're not alone.

This guide is (to my knowledge) the most comprehensive on annual planning, which has now become continuous planning, for startups. And to reflect the ethos of the guide, we'll continue to update it each year as we learn more.

Let's dig in.

Wishing you read my damn book,

CJ