I have been doing this with my kids’ pants for several years now. I also do this with skirts and shorts. Anything that goes around their waist, and I have done several trials and errors before this, so here goes:
1) I make the pants even on both sides, so they sit comfortably on my kids. If you want to make only one tab on one side, it will make the pants uneven and uncomfortable.
2) If you want to make the tab at the back and then sew it down, this will add a weird bump on the back of their pants and be very irritating while they sit or put on backpacks and coats. And they will complain to you about this.
3) If you leave the tab as they are, you can easily remove the thread when your kids’ waist catches up to the rest of their body. If you sew the tabs down, there is more thread to remove, and becomes trickier. Also, there is a higher chance that you will grab the wrong thread and make a hole in the pants – at which point you will need to read this tutorial on mending pants….
4) Also, if by some miracle, the pants do not get destroyed by the time they are grown out of, having only one simple sewn line on each side will not be very visible if you remove it and sell the pants on a mom-swap.
5) This method can be used on adult comfy pants, but… for some reason adult pants need to be loosened and not tightened… at least from my experience :p
6) Young kids are often more interested in comfort than style, or at least that is the case with mine. So if the fix you make is not comfortable, even their most favorite pants/skirt/shorts will not be worn again.
Thanks for the great tips, Katherine! My toddler is very tall but very lean so this info will def be helpful.
I do it on my kids pants all the time. I just redid a whole set of pjs they got for Xmas as the waists were just enormous! And now they can be worn and there are happy kids!