Here is a link to complete instructions:

https://www.tax.virginia.gov/sites/default/files/vatax-pdf/2019-760-instructions.pdf

104 Virginia529 Account Contributions - If you are under
age 70 on or before December 31 of the taxable year,
enter the lesser of $4,000 or the amount contributed
during the taxable year to each Virginia529 account
(Virginia 529 prePAID, Virginia 529 inVEST, College
America, CollegeWealth). If you contributed more
than $4,000 per account during the taxable year, you
may carry forward any undeducted amounts until the
contribution has been fully deducted. However, if you are
age 70 or older on or before December 31 of the taxable
year, you may deduct the entire amount contributed
during the taxable year. Only the owner of record for an
account may claim a deduction for contributions made