I have one of my husband's clients that is now my client that has several investment accounts, one of which had a significant capital gain. For some background info; my husband started this business about 30 yrs ago. I began helping him about 13 yrs ago, admittedly, he was a terrible teacher, preferring to just do it himself instead of teaching me the more complicated things. He recently passed away in the middle of tax season this year, before he could teach me more. So I've been researching and reading every tax book I can get my hands on to fill in the gaps, just to get me through this year, but I can't find an answer to this.

I filled out the sch D, as well as filling out the 8949 adding in the short and long term, including the investment fees as I was taught. I have attempted to call the IRS for clarification every day for the last 3 weeks and get the same recorded message: "due to extreme call volume, there are no agents available for your call, please try again on the next business day". To my knowledge, I have filled out everything correctly. The client is literally screaming at me, as due to the family trust having a capital gain of over 113k, they owe over 11k. He states that I did everything wrong and that he was told he would never owe taxes on that. So my question is, am I missing a form? Is there more I was supposed to do?