Yes, you are considered part of a plan at work.
"You’re covered by an employer retirement plan for a tax year if your employer (or your spouse’s employer) has a:
- Defined contribution plan (profit-sharing, 401(k), stock bonus and
money purchase pension plan) and any contributions or forfeitures were
allocated to your account for the plan year ending with or within the
tax year;"
Source:
https://www.irs.gov/retirement-plans/are-you-covered-by-an-employers-retirement-plan
