What Does a Fractional CFO Actually Do?

"What does a fractional CFO actually do?" comes up right before "do I even need one." The honest answer: a fractional CFO is the person who turns your numbers into decisions — the cash flow forecast that tells you whether you can make payroll in October, the pricing call that stops your best client from being your least profitable one, the hiring decision you make with data instead of a gut feeling. It's CFO-level strategy, part-time, priced for a business doing $1M–$5M in revenue instead of $50M.

The job in one sentence: bookkeeper records, CFO decides

A bookkeeper tells you what happened last month. A fractional CFO tells you what to do about it. Your bookkeeper closes the books, reconciles the bank feed, and produces a clean P&L. A fractional CFO takes that same P&L and answers the harder questions: Can we afford the account manager we want to hire in Q4? Is a 22% payroll-to-revenue ratio healthy or a warning sign? Should retainer pricing go up 8% or 15% on renewal? The CFO's raw material is clean books — which is why the engagement usually only works once the bookkeeping is already solid.

Five things a fractional CFO actually does each month

Cash flow forecasting. Most fractional CFOs run a rolling 13-week cash forecast, updated weekly or biweekly, that flags a cash crunch 60 to 90 days before it hits — early enough to fix it instead of scrambling.

KPI scorecard. A monthly dashboard tracking the five to eight numbers that actually predict trouble: payroll-to- revenue ratio, gross margin by client or project, days sales outstanding on receivables, cash runway, and CAC-to-LTV where there's a sales function. (See what a healthy payroll-to-revenue ratio looks like for agencies specifically.)

Pricing and margin analysis. Running true client-level or project-level profitability — not just top-line revenue — to find the clients quietly losing money and the ones that can bear a price increase.

Scenario modeling. Before a big hire, a new office, or an acquisition offer, building bear/base/bull models so the decision isn't made on optimism alone.

Board or investor-ready reporting. Monthly or quarterly commentary that explains the "why" behind the numbers, not just the statements themselves — the format a bank, investor, or potential acquirer expects to see.

What a fractional CFO doesn't do

A fractional CFO won't reconcile bank accounts or categorize transactions — that's bookkeeping. They won't manage day-to-day AP/AR processing either — that's a controller or bookkeeper function. A fractional CFO works one level up: strategy, forecasting, and the numbers-driven decisions that sit on top of books that are already accurate and current. Hire a CFO before the books are clean, and you end up paying CFO rates to first fix bookkeeping problems.

When agencies actually bring one in

It's less a revenue trigger than a set of signals: hiring your next senior role and unsure the payroll math works; retainer growth outpacing your gut sense of margin; considering a raise, a sale, or an acquisition and needing real numbers instead of a QuickBooks export; cash getting tight some months despite showing a profit on paper. See healthy margin benchmarks by industry for a sense of where your numbers should land before that conversation. Most fractional CFO engagements start between $1M and $5M in annual revenue — below that, the higher-value spend is usually still clean bookkeeping; above roughly $8M–$10M, many businesses have enough complexity to justify a full-time hire.

What it actually costs

A full-time CFO with agency experience runs $180,000 to $250,000 or more in salary alone, before benefits and equity. Fractional CFO services typically run $2,000 to $8,000 a month depending on scope — a quarterly advisory retainer at the low end, ongoing monthly forecasting and KPI reporting at the high end. That's roughly a tenth of the cost of a full-time hire, for the same strategic function most agencies only need 10 to 20 hours a month of.