Dependent Care contributions expired

[ill and annoyed]

I forgot to claim reimbursement for Dependent Care contributions before they expired. How do I correctly reflect this in my filing?

[RobertB4444]

You don't.   Dependent care reimbursements that were paid to you show up in box 12 of your W2.  Any dependent care reimbursements not paid to you should not be on there.  If the amount in box 12 reflects payments that you did not actually receive then you need to contact your employer for a corrected W2.