Guide to SaaS Financial Models: MRR, ARR, Churn and Cohorts

Canada has a deep and growing SaaS ecosystem. Toronto, Waterloo, Ottawa, Montreal, Vancouver and Calgary are home to thousands of software companies, from early-stage start-ups selling to small businesses to scale-ups serving global enterprises. Whatever their size, they all face the same question from investors and boards: is this recurring revenue healthy, and how fast can it grow?

A standard business plan template can't answer that. Selling software by subscription means today's revenue depends on customers won months or years ago, and on how many of them stayed, upgraded, downgraded or left. A good SaaS model makes each of those movements visible, so you can see whether growth comes from new sales, from existing customers, or is being quietly undone by churn.

This guide walks through how to build that model. We use a running example throughout: a Toronto B2B SaaS company with $100,000 in monthly recurring revenue, 125 customers paying an average of $800 a month, and a seed-stage plan to reach $2.5 million in ARR.

1. Why SaaS Models Are Different

• Revenue compounds. Each month's revenue builds on the customers retained from every prior month.
• Retention drives value. Small changes in churn have a large effect on long-term revenue and valuation.
• Cash and revenue diverge. Annual prepaid contracts bring cash upfront but are recognized as revenue month by month.
• Upfront acquisition costs. Sales and marketing are spent long before a customer pays them back.
• Investors value metrics, not just profit. ARR growth, net revenue retention and CAC payback often matter more than near-term earnings.

For the general principles of model structure, see our guide to financial modeling services. This article focuses on what is unique to SaaS.

2. MRR and ARR: Getting the Definitions Right

Consistent definitions are the foundation of a credible SaaS model. Investors will check how you calculate each one.

In our example, 125 customers × $800 ARPA = $100,000 MRR, or $1.2 million ARR.

3. Building the MRR Waterfall

The MRR waterfall, sometimes called the MRR bridge, is the engine of a SaaS model. It explains every dollar of change in recurring revenue each month:

A useful health check is the SaaS quick ratio: (new + expansion) ÷ (contraction + churn). Here it is $16,000 ÷ $3,000 = 5.3, well above the 4.0 often cited as efficient growth.

4. Churn and Retention Metrics

"Churn" means different things to different people. Define each metric clearly and report them together:

• NRR above 100% means existing customers grow revenue even with no new sales.
• Don't annualize carelessly. 2% monthly logo churn is not 24% annually; compounded, it means losing about 22% of customers in a year.
• Measure annual retention directly from cohorts once you have enough history, rather than relying on compounded monthly rates.

5. Cohort Analysis

Averages hide important patterns. Cohort analysis groups customers by the month or quarter they signed up and tracks what happens to each group over time. It answers questions averages can't: are newer customers sticking better than older ones? Does expansion start after month six? Is one acquisition channel bringing in weaker customers?

To build cohorts, export subscription data from your billing system (such as Stripe, Chargebee or your CRM) with customer ID, start date and monthly MRR. In the model, each cohort's retention curve then projects revenue from both existing and future customers, which is far more reliable than a single blended churn rate.

6. Unit Economics: CAC, LTV and Payback

Our example company spends about $144,000 a month on sales and marketing and wins 15 new customers, a blended customer acquisition cost (CAC) of $9,600. With $800 ARPA and an 80% gross margin, each customer contributes $640 of gross profit a month.

• CAC payback under 12 to 18 months is commonly considered healthy for SMB and mid-market SaaS.
• LTV:CAC of about 3x is a widely used benchmark; always state whether LTV uses revenue or gross margin.
• Burn multiple (net burn ÷ net new ARR) shows capital efficiency; below about 2x is generally considered efficient.
• Rule of 40 (revenue growth rate + profit margin) is often applied to more mature SaaS companies.

7. Canadian Details: BN Registration, HST, Deferred Revenue and SR&ED

Investors in Canadian SaaS companies check the tax and corporate foundation during due diligence. It starts with your CRA business number, the nine-digit identifier the Canada Revenue Agency uses for your corporate tax (RC), GST/HST (RT) and payroll (RP) accounts. Corporations incorporated through the Ontario Business Registry or federally generally receive a BN at incorporation; additional program accounts are added through BN registration on the CRA's Business Registration Online service.

Deferred revenue is a major cash advantage for SaaS. If our example company moves 40% of customers to annual prepaid plans, it collects up to a year of their subscription fees upfront, funding growth without new equity. Founders relocating to Canada to build a SaaS company should also read our guide to business plans for the Start-up Visa program.

8. From Metrics to a Full Forecast

With the waterfall, cohorts and unit economics in place, the model links sales capacity to new MRR, cohorts to retained MRR, and headcount and spending to costs, producing an integrated income statement, balance sheet and cash flow.

• Tie new MRR to sales capacity: ramped reps × quota × attainment, or leads × conversion for self-serve.
• Model runway monthly, including deferred revenue timing and SR&ED refunds.
• Run scenarios on churn, expansion and hiring pace; churn assumptions usually move valuation most.
• Present a one-page dashboard: ARR, net new ARR, NRR, GRR, CAC payback, burn and runway.

For how these numbers fit into a written plan, see our guide on how to build the financial section of a business plan.

9. Common SaaS Modeling Mistakes

• Counting one-time fees as MRR, which inflates ARR.
• Treating bookings or cash as revenue, ignoring deferred revenue.
• A single blended churn rate instead of cohort-based retention.
• Mislabeling NRR and GRR, or annualizing monthly rates incorrectly.
• New MRR that outruns sales capacity.
• Booking SR&ED as a monthly cost reduction instead of a delayed inflow.
• Missing CRA registrations, such as no HST account under the business number, which surfaces in due diligence.

10. Frequently Asked Questions