We will send you monthly reminders on the 25th of each month, and the window to submit a reading is from that point to the 1st of the new month. For example, we will email you on the 25th of June asking for a reading, and as long as you submit the reading on or before the 1st of July, it will be used for your monthly invoice. If the reading is submitted outside of this window, we will estimate your usage.