Add/Subtract Months on a Date in Ruby
With ActiveSupport you can easily add months (or days, years, etc) to a date with:
pry(main)> Date.today
# => Fri, 05 Sep 2025
pry(main)> Date.today + 2.months
# => Wed, 05 Nov 2025
pry(main)> Date.today - 1.month
# => Tue, 05 Aug 2025
But what if you're working outside of Rails and without ActiveSupport? You can use the shovel (<<) operator on dates to return the date n months earlier.
pry(main)> Date.today
# => Fri, 05 Sep 2025
pry(main)> Date.today << 1
# => Tue, 05 Aug 2025
If you want to go forwards, you can use >>, or negate the value of n using <<:
pry(main)> Date.today
# => Fri, 05 Sep 2025
pry(main)> Date.today >> 2
# => Wed, 05 Nov 2025
pry(main)> Date.today << -2
# => Wed, 05 Nov 2025