Self employed

You are correct about wanting to deduct local business mileage and after reading Pub 463, my belief is the tax home could either be the home residence or the most significant job, which if the job (pub 463 is ambiguous about the exact criteria) , would in this case likely be the 1099 job, either way traveling from home to the 1099 job would be considered commuting.

But as for the 1099 job to 1st W2 job (2nd trip) and travel from the 1st W2 to 2nd W2 job (3rd same day trip) why would that travel not be deductible when Pub 463 2024 (most current version), page 20 left column explicitly states:

"Two Places of work.

If you work in two places in 1 day, whether or not for the same employer, you can deduct the expense of getting from one workplace to the other"   (limited to the direct mileage between the two locations).

Page 19 of Pub 463 has the chart below which also explicitly shows that while travel from home to the main job is never deductible, travel to the 2nd job is Always deductible

The caution is to not use the chart if your home is your principal place of business, which is as I read it, if you actually have a "home office" which most don't, hence "Most employees and self-employed persons can use this chart."