If you explain more about the letter, you may get some suggestions in this forum, and I'll tell you how to use your Live feature below. But don't post any personal info in this public forum.
What tax year does the letter refer to--2018 or a prior year? What type of letter? Does it have a CP or LTR number in the right corner? What is the IRS alleging, and what do they want you to do.
Also, you appear to be using Live Self-Employed. If that's the product you used, then you paid extra for the Live feature, so you have the benefit of live help from a CPA/EA tax pro, if you want to talk to someone by phone.
FAQ: How do I connect with a tax expert in TurboTax Live?
<a rel="nofollow" target="_blank" href="https://ttlc.intuit.com/questions/4124827-how-do-i-connect-with-a-tax-expert-in-turbotax-live">https://ttlc.intuit.com/questions/4124827-how-do-i-connect-with-a-tax-expert-in-turbotax-live</a>
If you purchased the optional Audit Defense or MAX Defend & Restore, we can tell you how to contact the company that handles that, if necessary.