Please ask your employer for a corrected W-2. The W-2 is reported to the IRS so this means that your tax return will not match the W-2 that the IRS has.
Also, please confirm that your employer removed the should-have-been-Box-10 amount (your FSA contributions) from your Wages in Box 1 on your W-2. If not, then you paid income tax on that $5,000 when you should not have.
P.S. Note that Box 10 contains ALL the benefits paid to or for your FSA (even if more than $5,000). But the first $5,000 of such benefits are not included in Box 1.
The IRS says: "
Question
Should I include the amount in box 10, Dependent Care Benefits, of my Form W-2 when calculating my income?
Answer
Box 10 of your W-2 shows the total amount of dependent care benefits that your employer paid to you or incurred on your behalf. Amounts over $5,000 ($2,500 in the case of a separate return filed by a married individual) are also included in box 1.
"
See https://www.irs.gov/faqs/interest-dividends-other-types-of-income/employee-reimbursements-form-w-2-w...
