My husband sometimes gets paid to speak at colleges, how do I describe this?

You may use Guest Speaker or Public Speaker or Lecturer or Motivational Speaker. The IRS Business Code for All Other Professional, Scientific and Technical Services is 541990.

The IRS considers him self-employed and have your own business if: 

1.    You earn money as a contractor, consultant, freelancer, or other independent worker.

2.    You income is reported on 1099-MISC (Box 7), 1099-K (Box 1a), or you receive cash, check or credit card sales transactions, instead of a W-2.

When you have self-employment income, the IRS: 

• Requires you to complete Schedule C, Profit or Loss From Business.
• You can deduct expenses related to the income, like mileage (Vehicle expense).
• Requires you to pay self-employment (social security and Medicare).

If your self-employment income  was from cash or personal checks or credit card payments:

• Log on to TurboTax and click on the orange button, Take me to my return.
• Type sch c in the Search box.
• Click on “Jump to” link. 
• This will take you to where you can enter any cash, personal checks or credit card payments (Form 1099-K) related to your self-employment.
• You may be asked some general questions about your business. 
•  After you answer them, you’ll be taken to the Your XXX Business screen, click start/update on Business Income.
• On the Business Income screen, click start/update on General Income.
• Enter the income on the Tell us about additional income for your XXX work screen.
• You would also access the Business Expenses entry screens on the Your XXX Business screen.

If you received a 1099-MISC for your self-employed income: 

• Log on to TurboTax and click on the orange button, Take me to my return.
• Type 1099-misc in the Search box.
• Click on “Jump to” link.
• This will take you directly to the section where you can enter your 1099-MISC.
• You’ll also be able to enter any cash, personal checks or credit card payments (Form 1099-K) related to your self-employment.
• You would access the Business Expenses entry screens on the Your XXX Business screen. 

Related Information:

• What's the difference between self-employment income and other income?
• Where do I enter a 1099-MISC?
• Why am I paying self-employment tax?

If the speaker or lecturer has multiple engagements, should expenses get separated per engagement?  Example: if they lecture at University of X, and have income and expenses, then they are invited to speak at a conference in city Z and have income and expenses. Should each engagement be a separate Sch C or combine in one? Lecture or speaking engagements are finance related. 

No, it is not necessary to split expenses between the various speaking engagements because his business is already being classified as a guest speaker and/or lecturer. Just combine it into one.