That's correct (according to the Atkins center), but I would consider that a minimum amount of calories to prevent your body from going into "famine" mode. 10x your goal weight, assuming that it's a reasonable one, if the minimum amount of calories that you require to support your basal metabolism; you also have your daily activity level to consider as well as how much lean body mass you have. If you go below that your body starts thinking that food is scarce or a famine has begun and will adjust your metabolism downward to help you conserve energy and survive the famine.
For some people it can be a fine line. You don't want to eat so little that your metabolism gets lowered making it even more difficult to lose weight, but you also don't want to eat so much that you don't lose either. Having said that, most people on low carb don't have to worry too much about counting calories. Counting carbs is enough to keep the scale moving downward and the inches coming off. I would only worry about counting calories if I thought I was eating too little (and Fitday showed my calorie counts were consistenly low) or I wasn't losing at all for several weeks and Fitday showed I was eating far too much. A low or high day here and there aren't going to make much difference in the grand scheme of things.