If I understood correctly, you would like to show current year and next year value in drop down option in catalog item variable. If so please use below script :
Create On Load Catalog Client script:
var currentYear=new Date().getFullYear();
var nextYear=currentYear+1;
g_form.addOption('yourFieldNameHere', currentYear, currentYear,1);
g_form.addOption('yourFieldNameHere', nextYear, nextYear,1);
Please mark answer as Correct or Helpful based on impact.
