Starting Annual Recurring Revenue

What it measures

Starting ARR is the opening annualized balance for your period — the previous month's Closing ARR carried forward, unchanged. It is the annualized equivalent of Starting MRR and equals Starting MRR × 12. It is the fixed baseline against which you measure new, expansion, contraction, and churned ARR during the current period. It is not recomputed from active contracts; it is a direct reference to where last month ended, annualized.

Why it matters

You need a clean opening position because ARR movement only makes sense in context. Finance reads Starting ARR to anchor the bridge from prior month to current month and to set the denominator for growth-rate calculations. Operations uses it to set annual bookings quotas and churn budgets against a known base. Investors look at whether your opening ARR base is stable or volatile, since a noisy baseline makes every downstream growth rate and valuation untrustworthy.

How to read it

Starting ARR should be identical to the previous month's Closing ARR — no restatement, no catch-up. If the two numbers disagree, you have a data integrity issue, not a business event. Compare Starting ARR month-to-month to see if your annual run-rate is growing (good) or shrinking (last month's net-new was negative). Always pair it with month-end Closing ARR to read the *motion*: started at $1.2M, ended at $1.332M means +11% month-on-month. On its own, Starting ARR tells you almost nothing — its value is as the anchor for everything that moves on top of it.

What good looks like

Watch-outs

• Not locking it to the prior period's Closing ARR. Starting ARR must equal last month's ending annual run-rate exactly; any gap means the ARR waterfall no longer reconciles and growth-rate math is built on sand.
• Restating or adjusting it after the period has begun. Once the prior period closes, Starting ARR is frozen — corrections belong in the prior period's Closing ARR and only then flow forward.
• Confusing it with Closing ARR or the month's net-new. It is neither an ending run-rate nor a measure of motion — it is purely a carry-forward of where you started the period.
• Letting timing leakage contaminate it. A customer who signs on day one of the new month is New ARR, not Starting ARR; one who churns on the last day of the prior month is already excluded — misclassifying either inflates or deflates the opening base.

Worked example