He's Sensitive to Fabrics
Lots of kids complain about itchy tags, but some simply can't stand crooked sock seams, stiff jeans, new shirts, or bulky coats. They have a heightened sensitivity to fabric and feel almost as if they are being hurt when they wear something that isn't completely soft. If your child has an extreme aversion to clothing, making it difficult for her to get dressed, she might have a sensory processing disorder.
Playing dress-up with different types of clothes is a good way for picky kids to experiment with various textures. When you're shopping for your child, choose fabrics that breathe, like soft cotton, and go to stores that have a lenient return policy. Look for tagless clothes, or cut off any tags right away. Every evening, give your child a choice of what she wants to wear the next day ("Would you like the red dress with tights or jeans with boots?"), and lay out the clothes to avoid morning struggles. When you're introducing a new item, pair it with an old favorite. And think out of the box: If your child refuses to wear a heavy coat, let her wear a sweatshirt under a lighter jacket.