Should I go to the manager or the coworker first?

The coworker first, in almost every case. The exceptions are safety risks, harassment, or anything dishonest, which you should report straight away.

What if the coworker is senior to me?

The same steps apply, but frame it around shared work: "I want to make sure I'm not holding up your part. Can we check who's doing what?" Escalate to your own manager if it continues.

Do I need a real example?

Not for a "what would you do" question, but one short real example makes your answer more convincing. A school or volunteer example works.

What if they get angry when I raise it?

Say you'd stay calm, repeat the facts, and suggest talking again later. Your goal is to fix the work, not win the argument.

How long should my answer be?

About 45 to 60 seconds. The steps, one or two lines you'd actually say, and when you'd escalate.

What would you do if a coworker wasn't doing their share of work?

What the question is testing

This is a situational question: "What would you do if…?" There's no past story required, though a short one helps. The interviewer wants to know three things about you:

Will you complain or act? Some people grumble to others and do nothing.
Are you fair? Do you assume the worst, or check first?
Do you know when to escalate? Neither running to the manager on day one nor covering forever.

The order you describe matters more than any single step. A good answer climbs a ladder: facts, conversation, support, escalation.

The four steps

Check the facts. Is the work really not getting done, or is it just done differently? Are they overloaded with something you can't see? "I'd first make sure I'm not missing something, like a project they've been pulled onto."
Talk to them privately. Name the specific work and its effect, then ask. Assume there could be a reason.
Offer a fix together. Re-split tasks, agree a deadline, or set up a short check-in.
Escalate if it continues and it matters. Go to your manager with facts about the work, not a complaint about the person, and tell the coworker you're doing it.

Lines you could say

Interviewers remember answers that include real sentences. Here is what each step could sound like:

Step	What you might say
Opening the conversation	"Have you got ten minutes? I wanted to talk about how we're splitting the Friday orders."
Naming the issue	"The last two weeks, your half of the stock count wasn't done by close, and I finished it after my shift."
Asking, not accusing	"Is something making it hard to get to? I'd rather sort it out between us."
Agreeing a fix	"What if you take the morning count and I take the afternoon, and we check in at lunch?"
Before escalating	"It's still happening, and the store is noticing. I think we need to bring in Priya so the split is clear. I wanted to tell you first."
To the manager	"The stock count has been incomplete four times this month. We've tried re-splitting it. Could you help us agree who owns what?"

Notice the last line talks about the work and what was tried, not about the coworker being lazy.

Example answers

These are examples of the approach, with made-up details. Adapt them to the job you're interviewing for.

Example answer for an office job

"First I'd check I have the full picture. Sometimes someone looks idle on one project because they've been pulled onto another. If the work really isn't getting done, I'd talk to them privately, not in front of the team. I'd say something like, 'The client summaries for Monday haven't come in the last two weeks and I've been writing them on Sunday night. Is something getting in the way?' Often there's a reason, and we can re-split the work. If it kept happening and it was affecting deadlines, I'd raise it with our manager. I'd stick to facts, like which deadlines were missed and what we'd tried, and I'd let my coworker know I was doing it."

Example answer for a retail, hospitality or care role

"I'd speak to them on a break, one to one. I'd say, 'I've noticed the closing checklist hasn't been finished on your side the last few shifts. Is something going on?' Maybe they're new and don't know the routine, and I can show them. If it carried on and it was affecting customers or safety, I'd let the shift supervisor know, because that's not something I'd leave."

Example answer with a short past example

"This happened in a group project at university. One teammate hadn't sent anything for two weeks. I messaged him privately and asked if he was okay. It turned out he was working extra shifts. We gave him the slide design, which he could do on his phone between shifts, and moved research to someone else. We submitted on time. If he hadn't replied, I'd have told our tutor, because the grade was shared."

Mistakes to avoid

Mistake	Why it hurts	Try instead
"I'd just do their work for them"	Sounds kind, but hides the problem and burns you out	Cover once, then talk to them
"I'd tell the manager straight away"	Looks like you avoid hard conversations	Talk to the coworker first
"I'd ignore it, it's not my job"	Suggests you don't care about the team's results	Say when it becomes your business
Calling them lazy	Judgment without facts	Describe what wasn't done and its effect
Gossiping to other coworkers	Shows poor judgment	Keep it between you, then the manager

One exception: if the issue is safety, harassment or anything dishonest, say you'd go to a manager straight away. Interviewers in healthcare, finance and security roles often listen for that.

Practice it out loud

Situational answers can drift into long lists of "it depends." Keep yours to under a minute: the four steps, one or two quoted lines, and the exception. Say it out loud a few times so the quoted lines sound like you. Speaking Coach can play the coworker in a practice conversation, so you can try the hard sentence before you describe it in the interview.