PwC Tax Associate interview questions

I submitted my resume through a current employee and heard back fairly quickly that they wanted to conduct a phone interview. All the questions were behavioral in nature (Name a time when...) and fairly easy. About a week later I received an invitation to fly up to Boston for an in-office interview. I was one of about 50 people there to interview that day, although I'm not sure how many of those candidates I was actually competing against. Some people were there for assurance positions, or internship positions. Everyone was really nice and welcoming that I met. My morning consisted of a tour of the office and three individual interviews with various managers. Within a week of this visit I received an email saying that they would not be extending me a job offer. I was a bit perplexed by this since they had taken the time to fly me up and pay for my hotel room. Upon some prodding, the only feedback I could get from an HR rep was that I didn't have the experience they were looking for.