SaaS operating model
Sales capacity, ARR roll-forward, billings, unit economics. Build a subscription business from sales capacity to ARR to a quarterly P&L, reconcile cash to revenue through deferred revenue, and read the unit economics an investor will ask for.
Built in: Product and technology, Venture capital, Equity research and hedge funds
By Surojit Chakraverti, founder of L3VLUP and an investor running a long-short healthcare and technology equities strategy.
On this subject: saas operating model.Updated 2 October 2026
Who builds it, and for whatThe operating plan a software company runs on and the model a growth investor, a software equity analyst or a corporate development team rebuilds to test it: whether the sales force can close the ARR the plan needs, what retention does to the base, when the cash arrives against the revenue, and whether a customer pays back what it cost to win. The corporate three-statement frame does not carry over, and the model is built from the objects that do.
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| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Assumptions | |||||||||||||||
| 2 | $m unless stated. Quarterly periods, Y1Q1 to Y3Q4. | |||||||||||||||
| 4 | Quarter | Unit | Y1Q1 | Y1Q2 | Y1Q3 | Y1Q4 | Y2Q1 | Y2Q2 | Y2Q3 | Y2Q4 | Y3Q1 | Y3Q2 | Y3Q3 | Y3Q4 | Notes | |
| 5 | Scenario selection | |||||||||||||||
| 6 | Scenario | # | 1 | 1 = plan, 2 = downturn. Downturn inputs are marked below. | ||||||||||||
| 8 | Opening position | |||||||||||||||
| 9 | Opening ARR | $m | 24.0 | Annual recurring revenue at the start of Y1Q1. | ||||||||||||
| 10 | Opening customers | customers | 300 | |||||||||||||
| 11 | Opening deferred revenue | $m | 9.0 | |||||||||||||
| 12 | Opening productive account executives (AEs) | AEs | 8 | |||||||||||||
| 14 | Sales capacity | |||||||||||||||
| 15 | AE hires | AEs | 2 | 2 | 3 | 3 | 3 | 4 | 4 | 4 | 5 | 5 | 5 | 6 | Per quarter. | |
| 16 | Ramp period | quarters | 2 | Whole quarters, 1 or more, including the hire quarter. Checked on Checks. | ||||||||||||
| 17 | Ramping AE productivity, % of full quota | % | 50.0% | |||||||||||||
| 18 | Quota per productive AE, annual | $m new ARR | 1.2 | Quarterly capacity = annual quota / 4. | ||||||||||||
| 19 | Quota attainment, plan | % | 80.0% | |||||||||||||
| 20 | Quota attainment, downturn | % | 60.0% | Downturn: lower attainment, higher ARR churn, lower expansion; hiring unchanged. | ||||||||||||
| 21 | AE attrition, quarterly | % | 5.0% | % of opening productive AEs. | ||||||||||||
| 22 | Average new contract value, annual | $m per customer | 0.06 | Converts new ARR into new customers. | ||||||||||||
| 24 | Retention and expansion | |||||||||||||||
| 25 | ARR churn, quarterly, plan | % | 3.0% | % of opening ARR. | ||||||||||||
| 26 | Expansion, quarterly, plan | % | 4.5% | % of opening ARR. | ||||||||||||
| 27 | ARR churn, quarterly, downturn | % | 4.5% | |||||||||||||
| 28 | Expansion, quarterly, downturn | % | 2.5% | |||||||||||||
| 29 | Customer (logo) churn, quarterly | % | 2.5% | % of opening customers. Both scenarios; drives customer count and LTV. | ||||||||||||
| 31 | Billing and costs | |||||||||||||||
| 32 | Share billed annually in advance | % | 70.0% | Of new, expansion and renewing contracts; the rest is billed quarterly. | ||||||||||||
| 33 | Cost of revenue, % of revenue | % | 22.0% | Hosting, support and customer success. | ||||||||||||
| 34 | Fully loaded cost per AE, quarterly | $m per AE | 0.08 | |||||||||||||
| 35 | Marketing and sales support, % of new ARR | % | 35.0% | |||||||||||||
| 36 | Research and development, % of revenue | % | 28.0% | |||||||||||||
| 37 | General and administrative, % of revenue | % | 14.0% | |||||||||||||
| 38 | LTV horizon | quarters | 20 | Cap on customer life in the LTV calculation. | ||||||||||||
Select a cell to see its row, its schedule and the type of cell. Font colours: blue for inputs, black for formulas, green for links to other sheets. Scroll sideways to see every period.
Download
SaaS operating model: the workbook
Excel workbook with working formulas, no macros and no external links. Work with it above first; it is the same model as the preview.
What the base case says
- Closing ARR, Y3Q4
- $90.9m
- ARR growth, year on year to Y3Q4
- 61.5%
- Net revenue retention, four quarters to Y3Q4
- 107.3%
- CAC payback (months), Y3Q4
- 11.13
- LTV / CAC, Y3Q4
- 5.4x
- Operating margin, Y3Q4
- 5.8%
- Rule of 40, Y3Q4
- 67.3%
- Magic number, Y3Q4
- 1.8x
Read from the workbook as served, every input at its default. Periods: Y1Q1, Y1Q2, Y1Q3, Y1Q4, Y2Q1, Y2Q2, Y2Q3, Y2Q4, Y3Q1, Y3Q2, Y3Q3, Y3Q4. The figures are invented and move with whatever you type in.
What this model is
A quarterly operating model of a subscription software company over three years, Y1Q1 to Y3Q4.
Sales capacity sets new ARR; an ARR roll-forward adds expansion and removes churn; bookings, billings, deferred revenue and recognised revenue are reconciled; and a P&L runs to operating profit and operating cash flow.
Unit economics (CAC, payback, LTV, retention, magic number and burn multiple) are calculated from the same lines, and a downturn scenario shows the effect of lower attainment and retention on an unchanged hiring plan.
Seats: Product and technology, Venture capital, Equity research and hedge funds.
Careers that do this work: growth equity, venture capital, equity research, corp dev / m&a, bizops / strategy & ops.
How the schedules connect
Every row in the workbook is tagged with the schedule it belongs to; the inspector above shows the tag when you click a row. These are the schedules this model is made of and where each one lives.
Sales capacity
Reps, ramp, quota: the new ARR a team can close
Assumptions, row 6 · Assumptions, rows 15–22 · Sales Capacity, rows 6–12 · Sales Capacity, rows 15–19
ARR roll-forward
Opening, new, expansion, churn, closing
Assumptions, rows 9–12 · Assumptions, rows 25–29 · ARR Build, rows 6–14 · ARR Build, rows 17–21
Bookings, billings and deferred revenue
Cash before revenue, and the balance in between
Assumptions, rows 32–38 · Bookings & Billings, row 6 · Bookings & Billings, rows 9–13 · Bookings & Billings, rows 16–21
SaaS profit and loss
Gross margin, sales and marketing, R&D, G&A, cash
P&L, rows 6–16 · P&L, rows 19–21
Unit economics
CAC, payback, LTV, retention, magic number, burn multiple
Unit Economics, rows 6–12 · Unit Economics, rows 15–19
What you should be able to explain
- Why ARR is a stock moved by flows, and why growth is a sales capacity before it is a rate.
- How ramp, attrition and attainment turn a hiring plan into the new ARR it can actually produce.
- Why billings run ahead of revenue, what deferred revenue is, and why a SaaS company can burn less cash than its P&L suggests.
- How CAC, payback, lifetime value, net and gross retention and the magic number are read from the same lines rather than asserted.
- What the rule of 40 and the burn multiple summarise, and what they hide.
What a reviewer looks for
- Revenue grown at a rate with no sales capacity behind it.
- Churn and expansion applied to closing ARR, or expansion netted into churn so gross retention disappears.
- Revenue recognised when billed, which overstates the quarter a big annual contract lands.
- A lifetime value computed as margin over churn with a 1% churn rate, which produces a customer that lives a hundred years.
- Unit economics entered as inputs from a board deck rather than calculated in the model.
Conventions this workbook uses
Stated on the cover sheet too. A model is only as trustworthy as the decisions it tells you it made.
- Quarterly periods. Quotas, ARR and contract values are annual amounts; quarterly capacity is the annual quota divided by four.
- New ARR = (average productive account executives (AEs) x quota / 4 + ramping AEs x ramp productivity x quota / 4) x quota attainment. An AE ramps for the ramp period, counting the quarter of hire, and is fully productive from the quarter after it. Attrition applies to productive AEs only.
- Ramp period: a whole number of quarters, 1 or more (base case 2). A longer ramp keeps hires at ramp productivity for longer and delays new ARR; the Checks sheet flags any other value.
- ARR roll-forward: opening ARR + new ARR + expansion - churn = closing ARR. Expansion and ARR churn are % of opening ARR. Customer (logo) churn is a separate rate applied to opening customers; it drives the customer count and LTV, not ARR.
- Bookings are new plus expansion ARR contracted in the quarter. Billings are the annual-billing share of bookings and renewals due (a quarter of retained ARR), billed a year in advance, plus the remaining share billed quarterly as revenue is earned. Recognised revenue is average ARR in the quarter / 4. Deferred revenue = opening + billings - recognised revenue.
- Cash collections are assumed equal to billings in the quarter billed (no receivables). Operating cash flow = operating profit + change in deferred revenue, before tax and capital expenditure.
- Net and gross revenue retention are measured over a trailing four quarters, against opening ARR at the start of that window, and exclude new ARR. CAC, CAC payback, LTV, the magic number and the burn multiple are quarterly measures. The Rule of 40 adds year-on-year ARR growth to the quarter’s operating margin.
- LTV = quarterly gross profit per new customer (average new contract value / 4 x gross margin) x the lesser of the LTV horizon and 1 / quarterly logo churn. It is undiscounted and excludes expansion. CAC payback = CAC / quarterly gross profit per new customer, in months.
- Downturn scenario (selector = 2): quota attainment falls, ARR churn rises and expansion falls from Y1Q1. Logo churn, pricing and the hiring plan are unchanged, so the cost of continuing to hire shows in the efficiency metrics.
- Year-on-year ARR growth for Y1Q1 to Y1Q3 is measured from opening ARR at the start of Y1, as earlier quarters are not modelled.
Build it yourself
The starter workbook
The ARR Build sheet has been cleared: the ARR roll-forward from opening ARR through new ARR, expansion and churn to closing ARR, the growth lines and the customer roll-forward. Rebuild it from the Sales Capacity sheet and the retention assumptions, with expansion and churn following the scenario selector. The Checks sheet shows when ARR rolls forward in every quarter.
Blanks: ARR roll-forward. Free with any account. Compare with the worked model when you are done: download above.
The path around this model
Understand it, drill it, read the build, then apply it to a real company.
Build · Lab · ~12 min
Unit Economics
Build an LTV:CAC you could defend under questioning, and answer payback as its own question.
Build · Lab · ~12 min
Product Metrics Tree
Name the right north star for a product shape, and the guardrail your change would break.
Read · Guide · 11 min
SaaS Operating Models: ARR, Sales Capacity, Billings and the Metrics That Follow
Read · Guide · 13 min
How to Build a Three-Statement Model That Actually Balances
Apply · Skill
Model Audit
Find the errors in a financial model before someone senior does.
Apply · Skill
Company Profile
Build a banker-grade one-pager on any company, fast.
Vocabulary: ARR (Annual Recurring Revenue), Net Revenue Retention (NRR), CAC Payback, LTV to CAC, Deferred Revenue, Magic Number.
Questions about this model
What does the downturn case show?
Set the scenario selector to 2 and deals slip (attainment falls from 80% to 60%), churn rises and expansion falls, while the hiring plan carries on as it was. Closing ARR at the end of Year 3 drops from about $91 million to $60 million, net revenue retention from 107% to 91%, the magic number from 1.75 to 1.11 and the Rule of 40 from 67% to 43%. The same sales force is now buying less ARR per dollar, which is the first thing a software investor looks for.
Why is new ARR driven by sales capacity and not by a growth target?
Because the target is not what happens; the team is. Productive reps at a quarter of their annual quota times attainment, ramping reps at ramp productivity for the ramp period, and attrition on the productive base give the new ARR the company can close, and a plan that needs more has to hire earlier or sell more per rep. Building it this way turns a growth rate into a hiring plan someone can be held to.
What is the difference between bookings, billings and revenue?
Bookings are the value of contracts signed. Billings are the invoices raised, which for the share of contracts billed annually in advance arrive up to a year before the service. Revenue is the service delivered, earned evenly through the term. The gap between billings and revenue sits on the balance sheet as deferred revenue, and its build is why a growing SaaS company’s cash can be better than its profit.
How is lifetime value computed here?
Quarterly gross profit per new customer, counted undiscounted over the shorter of a fixed horizon (20 quarters) and the average customer life implied by logo churn. The horizon is the guard: dividing margin by a very low churn rate produces a customer that lives for decades, and no investor believes that number.
What does the magic number tell you that CAC payback does not?
Payback is per customer; the magic number is for the whole go-to-market engine: net new ARR in the quarter over the sales and marketing spent the quarter before. Above about 0.75 the engine is efficient enough to feed; below about 0.5 the company should fix sales before it hires more. They usually agree, and when they do not the difference is retention.
What does it cost?
Nothing to preview: the whole workbook is on this page, and a free account works with it online, every formula included. Every starter workbook downloads with a free account. L3VLUP Plus ($4.99/month) keeps one worked model each billing month, yours for good, and L3VLUP Pro ($25/month) keeps every one.
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