A costume is a face that moves wrong and a voice that sounds wrong, coming from a person your child cannot otherwise recognise. That is a reasonable thing to find frightening.
Stranger recognition sharpens hard somewhere between about eighteen months and three years old, right as costumes and masks become common everywhere. A toddler who happily waved at a stranger in June can genuinely struggle with the same face behind a mask in October. That is not a step backward. It is a skill arriving on schedule, at an inconvenient moment.
A child who has tried a mask on themselves, in the mirror, understands what a mask is before meeting one at a stranger's door. Skipping that step and hoping the night goes fine is the most avoidable mistake here.
Practising "trick or treat" at your own front door, with a family member in a hat rather than a mask, builds the script without the fright.
Carry them past the loudest houses instead of walking them. Let them ring one doorbell from a parent's arms rather than standing on the step alone. Going home after four houses instead of ten is not giving up — it is finding this year's limit, which is useful information for next year.
No. A costume is supposed to be fun. Comfortable clothes and a bag are a complete Halloween for a child who has decided against dressing up.
It usually eases the following year on its own, once the idea of a familiar person behind an unfamiliar mask has settled. Pushing exposure faster than a child is ready for tends to make the next year worse, not better.
Part of our guide to Holiday hosting with kids.