We choose our battles and how we fight them which includes those of the lying situations. Your son knows that lying on ANY level is pushing your buttons so for the little stuff (stealing candy from the kitchen jar) try turning it around to seem like it is no big deal but just needs a look at the boundaries.
For example:
You KNOW your son took some candy without asking.
1. As other's stated, take the tempation away - if he can't steal, he can't lie. "It is not working to have candy sitting out and about. It is being eaten too fast. So, for the time being, we will not have it just sitting around. If you want a certain type as a once a day treat or snack for school, let me know what it is and it will be rationed out." (Do not refer to WHO is taking it, just that it is disappearing)
2. Don't open up the power struggle by ASKING "Did you take candy?" You know the answer and it starts the fight.
3. You want to address that you KNOW there is missing candy but you don't want to come accross as automatically being judgemental and accusing your son. So, a few possible responses:
a. "Hmmm - looks like someone has a sweet tooth lately. I will need to limit candy intake or there will be more visits to the dentist to fix rotten teeth. Whoever has had more candy then normal lately, please make sure your are doing an extra good job brushing your teeth everyday." (even if you KNOW he didn't eat it but is hiding it)
b. "Hmmm - looks like someone has a sweet tooth lately. I think that someone may be saving his/her favorite kinds somewhere else in the house. We can not have candy stored where pets can get at it. Please let me know what type of candy you are looking for and we can work something out to make sure there is enough during the week."
c. "Everyone, please return any candy you have store in the house."
d. difficult child states he was going to count the candy. Purchase individually wrapped candies and ask him to count them before putting them in the jar. He can count them every day and keep a tally of the total if he wants. (He may not want to do this but it is an option to offer to him to meet his need to count. Even though that was just a lie, you are sending the message that you want to provide opportunities to him to do things he likes without getting into trouble). He will be caught off guard if you give him an alternative to meet what he says the reason was instead of punishing for stealing or lying. "That was not the right thing to do, so instead, you can ........." No punishment, just redirection. You are teaching him problem solving - he can find ways of doing things without lying and stealing about it.
When Diva was about 12/13, we did a lot of, "Well, that does not appear to be working, let's try another way." Some of those included pulling in the boundaries - I had given her too much rope and it didn't work. I did not get angry with her, just looked at the situation and redid some rules. (That is common as our kids grow and are not always able to handle what we think they are ready for)
As much as possible, try not to give him an opportunity to lie. This means looking at every question you ask him and maybe rephrasing it. Instead of, "Do you know where my gloves are?", say, "Can you help me find my gloves?" Instead of, "Did you take the phone?" ask, "Can you help me find the phone."
Start board game nights. You may be able to gauge his level of "lying" while playing games. I think you may be able to tell in time if he is becoming more trustworthy through the board games. They can teach him that winning in an honorable way is a good thing. One good game is Cadoo - part of the game has the player looking through the house for items. That would be a great way for you to praise him for how well he can find things opening up his willingness to "find" missing things when you are looking for them. "I can't find _________, difficult child, can you help me look?"
As others have indicated, negative punishments/disciplines often backfire and make things worse. Whenever possible, be positive - stay calm and make it appear that you are being objectional instead of personal about finding an answer. (You are looking at the SITUATION and not at looking for blame). He wants you to acknowledge that he had the power to make you angry by lying to you so try to get to the answer without that blame involved.
Make every situation a learning event as much as possible instead of a punishing event. That was not right, what should have we done instead?