that’s a bit complicated. It depends on whether or not you have a “regular place of business“ as defined by the IRS, and where that is.
If you have a regular place of business, such as the pharmaceutical company, then mileage to, and from your regular place of business, is never deductible. That’s considered commuting, and commuting is not deductible. All the other mileage you drive on your courier trips would be deductible business miles. If your last trip of the day is from the last drop off directly home, and you don’t stop by the pharmaceutical company, then the last trip home is deductible mileage minus the number of miles it would have been, if you went to the pharmaceutical company first. In other words, if the pharmaceutical company is 5 miles from your home, then the first trip of the day to the pharmaceutical company is not deductible, and the last trip home is deductible minus 5 miles.
If your regular place of business is in your home, then all of your mileage is deductible. To have a regular place of business in your home, you must generally qualify for the home office deduction. If you are a courier, you might be able to designate your home as your regular place of business if your home is where you do the administrative portion of the job. In other words, making appointments, planning routes, doing your bookkeeping, your billing and invoicing, etc.
If you have no regular place of business, then, your first trip out in the morning, and your last trip back at the end of the day are considered your non-deductible commute.
The rules are in chapter 4 of publication 463.
https://www.irs.gov/publications/p463#en_US_2022_publink100033925
