Months elapsed
This template displays the months elapsed from the date selected in the date field of your choice until today.
If the field does not have a value, โNoneโ will be displayed.
For the parameter Date field, pick the Date field that should be compared against the current day.
Configuration
To use the Months elapsed template, simply select it from the template grid. Filter by Misc to find it faster.
Parameters
To complete the configuration, select values for all parameters.

Expert mode
If you switch to Expert mode you can see the Smart field in the Expression Parser. You can now tweak the expression to create a custom smart field based on this template.
Expression
General expression:
%{{issue.cfnnnnn} != null ? ((year({system.currentDateTime}, RUN_AS_LOCAL) - year({issue.cfnnnnn}, RUN_AS_LOCAL))*12 + month({system.currentDateTime}, RUN_AS_LOCAL) - (month({issue.cfnnnnn}, RUN_AS_LOCAL))) : null}
NNNNN is the ID of the custom field you chose for the โDate pickerโ parameter.
Format
Default
Used parser functions
The links lead to the JWTC documentation because the parser functions are shared functionalities.