# customer / churn

### Initial period

$t_0$ (pay something at $t_0$)

--> you're considered a paying customer if you're still there at $\tau(t_0)+1$ (the end of the period in which you started)

### Terminal period

* churn in month; counted as customer for that month

**Case 1**
* start in Jan
* churn in Feb

marked as customer Jan, feb

--> Jacob does this

**Case 2**
* start in Jan
* churn in Jan

marked as customer Jan

--> Jacob does not do that

-------------------

(monthly granularity)

* Sub in Jan
* Churn in Jan
* --> not customer
* --> no recognised revenue

* Sub in Jan
* Churn in Feb
* --> customer in Jan
* --> not customer in Feb
* --> recognised revenue in Jan

(yearly)

* sub in 2022
* churn in 2022
* --> not customer
* --> no recognised rev

* sub in 2022
* churn in 2023
* --> customer in 2022
* --> recognised revenue in 2022
* --> nothing in 2023