Contributions made to a 529 plan are entered as part of your state return. Each state has different rules regarding carryover contributions, but if your state allows a carryover then the entry should be part of the 529 contributions page in your state return.
If you are having difficulty finding that exact entry, please share the state you are filing and someone can guide you to the right place.
To report 529 carry over contributions on your VA return:
Invest529 account owners who are Virginia taxpayers may deduct contributions up to $4,000 per account per year with an unlimited carryforward to future tax years, subject to certain restrictions.