Quick fix: If you can, tink the bind off back and redo it on a needle 2 sizes larger. If the piece is finished, pick up stitches along the bound-off edge with a larger needle and work one loose bind-off row.
What you are seeing
The top edge of your knitting pulls inward — puckered, rigid, and narrower than the rows below. A neckline bound off this way may be impossible to pull over your head, and cuffs won't slide over hands.
Why it happens
- Pulling too firmly when passing each stitch over the next during the bind off
- Using the same needle size for binding off as for knitting when more ease is needed
- Standard bind off used on an edge that requires stretch (necklines, sock tops, cuffs)
Fix it now
- Tink the bind off by inserting the left needle into the stitch below each bound-off stitch and slipping stitches back, working in reverse.
- Switch to a needle 2 sizes larger and redo the bind off, holding the working yarn loosely.
- Alternatively, use the k2tog bind off: slip 1, k1, psso, then k1 and psso again — repeat. This creates a reliably stretchy edge.
- For a finished seamed piece: pick up stitches along the edge using a larger needle, work 1 row, then bind off loosely.
Prevent it next time
- Always bind off necklines, armholes, and cuffs on a needle at least 2 sizes larger.
- Use a sewn bind off or Russian bind off for maximum stretch on sock and sock-adjacent projects.