Vintages and retention

Vintage = month of the first confirmed payment: first paid subscription invoice, first disbursed advance or first paid monthly fee of the contract. Sign-up, proposal or contract signing date does not open a vintage, because some people sign up and never pay. State the rule in the context document and check that the code uses the same one.

Score, risk tier, channel, campaign and employer used to slice the curve come from the first version of the record (the oldest by update date) or the version valid on the entry date in the history. The current record changes later: the score goes up, the channel gets corrected.

Generate one row per customer and calendar month since the vintage, with zero where there was no payment. MoB = months between the vintage and the month. Months before the vintage and customers with a deleted account are flagged (MoB -1) and left out of the curves.

The same customer may have more than one account or contract. The curve is per customer (master id or tax ID), adding all accounts; the account shown is the first one. Subscription and advances may have different vintages: keep one MoB per product and say which one the curve uses.

Add only amounts actually paid: invoice with success status, fee with confirmed payment, amount collected on the advance. An open invoice is not revenue, not even when the paid amount is zero and the billed amount is filled. In protection, use only the monthly fee (monthly invoice type), without canceled invoices. A repeated invoice in the same month for the same subscription counts once.

In the reference month, separate what fell due and was not paid (collection date before today with an error or partial payment) from what is awaiting payment (collection in the future). Only past due enters vintage delinquency. Vintage delinquency at MoB k is the past-due unpaid amount / amount disbursed to the vintage, and the migration between buckets from one month to the next is the roll rate.

State which statuses close a customer (for example, inactive, canceled and canceled with pending items) and use the date of the change to that status. In subscriptions, end = cancellation, or the last paid month if later. Delinquent is not an end until it becomes canceled. Every final status counts: leaving plain canceled out removes exactly those who left.

Whoever is still active has open retention. Average retention is computed only among closed contracts, or with a survival curve (percentage still active in each month since entry). Never mix closed contracts with active ones measured up to today.

Compare MoB 3 of one vintage with MoB 3 of the others. Only customers who have had time to reach a MoB enter its denominator. The current month's vintage has not closed its first month yet. Churn in a rolling window (exits in the last 30 and 90 days) is another metric, recomputed on every run, and does not replace the curve.