Free cash flow conversion is the underwriting bar in B2B SaaS.

There is a comfortable narrative in B2B SaaS that gross margin is the durability metric, that ARR growth is the value creation metric, and that free cash flow is something to worry about later — once the business has scaled, once the infrastructure investment is amortized, once the GTM motion is mature. On a fund-clock holding period, that ordering is defensible. On a permanent-capital holding period, it is not.

The longer we intend to hold a business, the more the value of the business converges on the cash it actually produces for its owners. Multiple expansion fades as a value driver. Re-rating to a comp set fades. What remains is the compounding stream of free cash flow the business throws off, net of the reinvestment required to keep it competitive. This piece walks through the conversion bar we underwrite to and why every other B2B SaaS metric we track is, ultimately, a leading indicator of it.

The metric, defined

We define free cash flow conversion as free cash flow divided by GAAP operating income, with both numerator and denominator normalized for one-time items. The numerator deducts maintenance and growth capex, capitalized internal-use software development costs we believe should reasonably be expensed, and the cash impact of working capital movement across deferred revenue and accounts receivable. The denominator adds back stock-based compensation only to the extent the business could plausibly issue equity to pay for the underlying labor without dilutive impact a long-hold owner would object to.

That is more conservative than the conversion ratios most B2B SaaS companies disclose. Public software companies routinely publish "non-GAAP free cash flow" that ignores stock-based compensation entirely and capitalizes large pieces of the engineering organization. On a one-year basis, those numbers are defensible. On a twenty-five-year basis, they are misleading, because the cumulative dilution and the cumulative capex catch up with the model.

The bar: seventy-five percent steady-state conversion

Our underwriting requires a credible path to seventy-five percent free cash flow conversion within a defined window — typically two to four years from acquisition, depending on the starting point. That number is not a headline target; it is what we put into the model as the steady-state assumption before we run the discount.

On a permanent-capital horizon, the cash conversion ratio is not a balance-sheet metric. It is the business model.

Why seventy-five percent and not, say, ninety? Because the kinds of B2B SaaS businesses we want to own are still reinvesting. Reinvestment is what produces the next decade of compounding NRR and the next decade of share gain. A business converting ninety-five percent of operating income to cash is usually a business that has stopped investing in itself, and that is not the asset we are looking to hold for twenty-five years.

Why seventy-five percent and not, say, fifty? Because below that bar, the business is structurally consuming the cash it produces, and a long-hold owner can no longer rely on the operation to fund either reinvestment or distributions in a normal market environment. The business becomes dependent on capital markets we do not control, on a holding-period timescale we cannot match. We covered an adjacent version of this argument in How we underwrite a software acquisition for a 25-year hold.

The four reconciling items we focus on

On every deal, the gap between reported operating income and underwritten free cash flow comes down to a small set of items. We pay disproportionate attention to each one in diligence.

1. Capitalized internal-use software

Many B2B SaaS companies capitalize a meaningful portion of their engineering payroll under ASC 350-40. Done conservatively, that is appropriate accounting. Done aggressively, it can flatter operating income by ten or more points. We rebuild the schedule bottom-up in diligence, and the underwriting model uses the rebuilt number, not the as-reported one.

2. Stock-based compensation

On a long hold, stock-based compensation is real cash. Either the business buys back shares to neutralize dilution, or the owners' percentage of the compound erodes over time. We model SBC as if it were cash expense at the steady-state target compensation mix, not at whatever artificially-low cash compensation the company may currently use to backfill into equity grants.

3. Working capital and deferred revenue

Healthy B2B SaaS businesses with annual prepaid contracts generate a real and recurring working-capital tailwind from deferred revenue. Less healthy businesses rely on that tailwind to flatter cash flow in growth years and watch it reverse painfully when growth flattens. We separate the steady-state working-capital tailwind from the growth-driven one and underwrite only the former into long-run conversion.

4. Maintenance versus growth capex

Most B2B SaaS businesses do not have meaningful traditional capex. The ones that do — the data-intensive vertical SaaS we like, in particular — usually under-disclose maintenance capex inside a larger growth-capex line. We split it in diligence and apply only the maintenance portion to steady-state conversion. The growth portion is treated as what it is: a discretionary reinvestment decision.

How conversion changes the operating posture after close

Underwriting to a conversion bar is not just a diligence exercise. It changes how we operate the business after we own it. Brands inside the portfolio are evaluated each quarter on their progress against a conversion glide path agreed with the operator at close. The glide path acknowledges that some brands need a year or two of additional investment before conversion improves; what it does not allow is indefinite deferral. The path has dates on it.

That has practical consequences. We will pre-fund a brand's sales build, a platform migration, or a security investment that depresses near-term conversion if the operator can show the path. We will not pre-fund those investments quarter after quarter without movement on the path itself. The discipline is the same one we wrote about in The first 100 days — change what compounds, leave the rest alone.

What disqualifies a business from our process

We pass on businesses where the gap between reported operating income and underwritten free cash flow cannot plausibly close. Three patterns recur.

• Structural SBC dependence. Businesses where the cash compensation required to retain the team, absent equity grants funded by an acquirer or public market, exceeds the operating income line.
• Capex masquerading as opex. Businesses whose hosted infrastructure costs grow super-linearly with revenue and have been quietly absorbed inside cost of goods sold, rather than disclosed as capacity capex.
• Working-capital fragility. Businesses whose reported cash flow leans heavily on annual prepaid contracts that diligence reveals to be year-over-year renewing rather than truly multi-year, leaving the tailwind one bad renewal cycle from reversing.

Each of those is a case where the headline ARR and headline gross margin can look attractive while the cash conversion path does not exist. We pass even when the deal is otherwise appealing, because the math does not work over our holding period.

Why this is the right north star for our structure

Public software investors can rely on multiple expansion and re-rating to drive returns over a five-year window. Private equity owners can rely on a second sale at a higher multiple in seven. Permanent-capital holdcos cannot rely on either. Our return is the cash the businesses produce, plus the compound that cash creates when reinvested at the operator level. Free cash flow conversion is not one metric among many for us. It is the through-line of every other metric we track.

We tied the broader thesis together in Permanent capital is the only sane structure for software. The conversion bar described here is the unromantic version of that argument: a structure built for compounding only works if the underlying assets actually compound in cash, not just in narrative.

The bottom line

Free cash flow conversion is the metric a permanent-capital operator can least afford to ignore and the metric most B2B SaaS companies talk about least. We have made it the underwriting bar and the operating north star inside our portfolio. Investors who want the full underwriting framework, including how the bar interacts with our portfolio-construction logic, can reach out here.