IMO it's not really a case of what exact time is cut off for carbs, for me it's more about how much carbs are you consuming per day. And the larger portions go in the morning. There's no way I can eat dinner w/out carbs and enjoy it. I just make sure it's a very small portion of it. Some of these guys that say, "no carbs after 3pm go to bed at 8pm. I've seen posts like that.
If you'd like to play it safe go low carb, and for dinner eat a very small portion of complex carbs. And remember if weight loss is your goal, it doesn't matter if you eat carbs after 3pm or 10pm, if you're not calorie deficient you are not going to lose the weight.