Maybe/app/models/account/balance.rb

class Account::Balance < ApplicationRecord
    include Monetizable

    belongs_to :account
    validates :account, :date, :balance, presence: true
    monetize :balance
    scope :in_period, ->(period) { period.date_range.nil? ? all : where(date: period.date_range) }
    scope :chronological, -> { order(:date) }
end