Were do I list our equipment expenses? My husband retired in November and started a business in December of 2024. At this point he is sole proprietor.

In December, was he open for business and operating or was he just preparing for business?  If he was open and operating, then you can list these expenses on Schedule C as expenses and assets depending on what they are.  You will need to use TurboTax Home and Business or TurboTax Premium to file the schedule C.

If he was not open and operating the business in 2024 and these were expenses incurred in preparation for opening in 2025, they would be considered start up expenses and would not be reportable on the 2024 return, instead they would be included on the 2025 return. If they are assets, and not minor expenses, you would still wait to depreciate them until you actually put them in use. 

Reporting Self-Employment Business Income and Deductions