Employer Tuition Assistance

You do not. 

Employer Tuition Assistance. Up to $5,250 in employer-provided tuition assistance, also known as employer educational assistance or employer tuition reimbursement, can be excluded from an employee's income each year. Eligible expenses include tuition, fees and course materials like textbooks, supplies and equipment.

If your tuition reimbursement is $5,250 or less, your employer should not include it on your W2 and you do not have to pay taxes on it.

If the employer provided assistance given in 2019 is $5,250 or less, and that amount was paid directly to the school by the employer, then it's not included in box 1 of your W-2. However, it will be included in box 5 of the 1098-T you receive from the school. It's a scholarship the school received on your behalf, as far as the school is concerned. So the amount received by the school from your employer is included in box 5 of that 1098-T.

If the employer paid it directly to you *AND* included it in box 1 of your W-2, then it's taxable income to you already. The taxability of it will be offset by the qualified education expenses you used that money to pay for in 2019.