I was assigned multiple projects at work and one of the projects my boss is asking what took so long to complete. The project he is referring to was reassigned to me with not enough information to start and because I was busy with other projects I did not follow-up to get all the details. Once I received all the details I was able to complete the project quickly but only after he sent an email asking why its not completed. After I finished the project he sent another email asking what took so long. I am not really sure how to respond to that.
First, you need to realize that when your boss asks you this, you already have a problem. You are in a hole now and it's important to do the right thing to get out of it.
Back when things started to slip from your plan and your schedule, you needed to inform your boss, things like "I still don't have xyz from abc so we are now going to be late with def" or "the reports have taken a lot longer than I expected, so I'm two weeks behind, and I don't think I'll be able to make that up while I do the rest of the project, so it will finish two weeks late." Or perhaps when your boss asked you to take on an extra task, you could have replied "I can do that, but it will delay my work on ghi by at least a week." Bosses don't always keep track of all the moving parts, and may assume that you accepting work means that you have time for it in your current workload.
I hope you took good notes and know what the issues were. As your boss, I would be interested in knowing what we need to do to prevent this next time. Is it that you took more work hours to complete the task than I thought it would take? Is it that you were blocked or delayed by other people so it took more elapsed time? Is it that you have a lot of things to do so you weren't able to put time in on this project? Is it that you just plain don't work hard enough? Without whining or making excuses, you need to clearly demonstrate what happened. Pay attention to measurable facts like:
- the original estimates or guidelines or deadlines you were given for each task. Both the effort (eg 40 hours) and the elapsed time (eg two weeks if you put half your time into it.)
- the actual effort and elapsed time you spent
- any delays where you couldn't work on it at all, or enough, and why
- any rework or times when you spent more effort than you had planned to, and why
- any reporting you did to your boss about delays, extra effort, or other work keeping you from getting to this work
It would probably help if you also had a plan for what you will do in the future to prevent this, such as reporting delays caused by others more quickly, not planning to put 8 hours a day on a project when you know you will have support duties while you're doing the project, getting some training on something you're slow at, and so on. If some of that plan has already been put into motion, even better.
Answer it factually. List what he assigned you and the priorities those tasks were given, list how much time each one took and (as exactly as possible) why it took that much time (remember to include time lost to things like mandatory meetings), and ask him whether he can offer suggestions that might speed it up next time, or how priorities can be better set/recognized/communicated next time, or whether there's a better way to estimate how long a group of tasks will take to complete.
It's his job to push you to improve, but also his job to guide you toward improvement.
If you take the time to put together a reasonable answer, you usually don't have to be afraid of this question.
If you continue to be overloaded and expect it to be an issue again, a useful pattern is "Sure, I can take that on, but since I'm already at capacity something else is going to have to slip to make room. What's its priority relative to...?" Don't invoke it when you don't need to, but don't promise more than you believe you can accomplish either.
List the issues and challenges that you ran into while completing the project, what you did to resolve them, why the resolution process took time e.g. you had to work out an answer from scratch and you had to test to validate it and of course, you had to work out how to design the tests. You can conclude that some of the issues and challenges (list them) were one-offs i.e. you know what you have to do the next time and that others ares bound to recur (list them).
Be clinical, dispassionate and thorough - This is how you are communicating that you are competent. Make no excuses, if you screwed up somewhere, say so. Better some damage to your boss's high perception of you than losing your credibility with the boss - You want to get to the point where if there were a FUBAR and you had nothing to do with it, he takes your word without a murmur.
Keep track of how long your projects are taking. If one or more of your projects falls behind schedule, notify your boss immediately and tell him what the challenge is - the boss has resources to back you up that you don't have, and he can make decisions that you can't make e.g. postponing the project, putting it on a lower priority or putting other projects on a lower priority so that you can complete this project on time, or extending the deadline on your project. I suspect that you failed to keep the lines of communication open with your boss regarding your progress on your projects and that's why he is now asking for an accounting.
I can't see why different projects taking different time to finish would be surprising to your boss. They are, by definition, not the same. If some took longer than planned, that's a different issue.
Either way, stick to the facts. From what you're saying (btw you might want to edit and add a few more details so we can answer you better) there is no reason to assume your boss is asking in an "hostile" way (like "ok, so where did you fuck up?"). Maybe he just wants to know what happened so he can plan things more accurately next time, and/or divide the tasks in a more efficient way