Only certain ties with certain matching kilts, and always with the tie separated/covered in large part by a nice solid waistcoat. And I honestly do NOT do it very frequently with the ties.

I also adhere to the concept Jamie espouses of never wearing more than one matching tartan accessory with the kilt at any one time---same distribution, flashes, tie, flatcap (sorry Jock, I'll cover the cost of the nitroglycerin for your chest pain), or plaid.

jeff