Retirement plan covered at work

[Julia22]

Last year, I only worked from Jan to July and then became unemployed. At work, the company provided 401k plan option but I didn't contribute since the company did not match. There were RSU and ESPP benefits though. Now I am considering contributing to traditional IRA if I can get tax deduction. What puzzled me is I am not sure if I am considered "covered by an employer's retirement plan".

I saw somewhere says:

"As a general rule, you are considered covered for a given year only if you or your employer makes a contribution on your behalf...The Form W-2, Wage and Tax Statement, that you receive will have a check in box 13, “Retirement Plan” if you are covered by a plan of that employer."

Box 13 is unchecked on my W-2. 

[FangxiaL]

If your Box 13 is unchecked, you should be able to deduct your Traditional IRA contribution regardless of your income. You are not considered covered by an employer's retirement plan. Sometimes, Box 13 is checked even if an employee did not make any contribution. I have seen both situations.