The Halacha does not consider the wearing of any item defined as clothing as carrying in a public domain on Shabbat. The Shulhan Aruch rules that it is even permitted to wear two of the same type of garments simultaneously, and this is not tantamount to carrying. One may wear two shirts, jackets, pairs of socks, scarves etc., one over the other, even if his intention is to bring the extra garment to someone else. Likewise, there is no issue of wearing a hat over a Kipa.
The Shulhan Aruch extends this leniency to wearing two belts. However, the Rama disagrees and only permits wearing the second belt if worn in a different place on the body or separated by an intervening garment. According to the Ashkenazim, who follow the Rama’s ruling, there is a debate with regard to the Hasidic custom of wearing a Gartel, the special belt designated for Tefila. Rav Moshe Feinstein (Russia – New York, 1895-1986) in Iggerot Moshe rules that it is prohibited to wear in the public domain, since it is a belt over a belt. Even if it would be in a different place, he is still stringent, as he does not consider the Gartel to have any significance as a garment. It is only a ritual item with significance during prayer. Rav Yishak Yaakov Weiss (London- Jerusalem, 1901-1989), in his Minhat Yishak is lenient and offers an interesting Sevara (analysis). He holds that the Gartel has inherent significance as a distinguished garment, and that is why it is customary to wear it for prayer. This is opposed to Rav Moshe’s view that it only has significance when used for prayer.
It is permitted to wear a Talit in the public domain, because it is a garment. Clearly, there is also no problem of wearing a Talit Katan at night, since it is normally worn then. However, the question is whether it would also be permitted to wear a Talit Gadol out at night, which is not the ordinary time. Would the Talit then be considered a burden carried, and not a garment worn? The common application would be someone going to the Nes Minyan, and leaves his house wearing his Talit before dawn. The Aruch Ha’shulhan (Rav Yechiel Michel Epstein of Nevarduk, 1829-1908) is stringent and prohibits this, except for Yom Kippur, when everyone wears his Talit at night. However, the majority of the Poskim are lenient and do not differentiate between a Talit Gadol and a Talit Katan. Perhaps it is analogous to wearing a raincoat, which is permitted even when it is not raining outside.
Wearing a Talit is permitted, because the strings, although not a garment, are considered Batel (subsumed) to the cloth of the Talit. Even if the Talit is made of cotton or nylon, which is only obligated M’drabanan (Rabbinically), they are still Batel. The Shulhan Aruch deals with the question of wearing a Talit whose strings are Pasul (not valid). Besides the prohibition of wearing a four- cornered garment without Sisit, he is also violating the prohibition of carrying. Once the strings are invalidated, they no longer serve as Sisit. At the same time, they retain their significance to the wearer, since he intends to save them and fix them. Therefore, they are not Batel to the garment and are being carried.
A more common application of this principle would be a person who discovers a dangling button on his shirt. Theoretically, it could be argued that the button is being carried, as it is no longer Batel to the shirt. On one hand, it no longer functions as a button, and on the other hand, the person intends to keep the button to re-sew it after Shabbat. This creates a dilemma, since a person would have to remove his shirt in such a case. The Poskim suggest a solution that the person have in mind not use the button after Shabbat, thereby nullifying its significance. That way, it becomes Batel to the shirt.
The Poskim also discuss the zipper for the inner lining of a coat. Even when the lining is not installed, it is also considered to be Batel to the coat.
• It is permitted to wear two items of the same garment simultaneously, in the public domain. Sepharadim may even wear two belts.
• It is permitted to wear a Talit Katan and a Talit Gadol at night in the public domain.
• If one discovers a dangling button from his shirt, he should have intention to discard that button after Shabbat.
• The zipper of the inner lining of a coat does not present a problem on Shabbat.