Tuition reimbursement counted as federally taxable income?

[worck]

My W2 does not seem to include my company tuition reimbursement even though I had 10k in education costs.  Is this right and do I still need to add as additional income somehow?  Also, can I enter 1098t form for educationa?

[MichaelMc]

Amounts received by an employee under a written educational assistance plan are excluded from taxable income, up to $5,250 per year. 

The amount received should not be included in Box 1 of Form W-2.

The general rule is that no "double benefits" are allowed. You may still be able to claim some portion of the American Opportunity Tax Credit or the Lifetime Learning Credit. However, the amount reported in Box 1 of Form 1098-T must be reduced by the amount of any tax-free educational assistance received from your employer

For more information, please see IRS Pub. 970 Tax Benefits for Education.

[worck]

This great but how do I know how much was tax free?  I know the first 5k or so is tax free but whatever the rest?  Is it tax free or not?  I am not sure since not in W2 but perhaps taxes are still collected from paycheck?