I am making some apps for our operations team, where we have to generate reference numbers.

Eg. 

Company Name: Acme Corporation

Application: Payment Receipt

Current Month: January

Curent Year: 2018

and auto number

so the reference number will be AC/PR/JAN/2018/001 next AC/PR/JAN/2018/002

Currently i have pre-populated the field AC/PR/JAN/2018/ and expect the user to add the last digit but there are chances of mistakes and each month i have to change the month.