If by "retirement savings account" you mean a 401(k) or other employer-sponsored plan, then you'll only have a reporting requirement if she took a distribution from the account.
As long as the funds remain in the account -- even if they continue to grow -- then they are not considered taxable income. But once she takes a distribution, then the account custodian will issue her a form 1099-R, which will have to be reported on that year's tax return.