"If you are in the 12% tax bracket, then you are in essence getting a 12% discount on the 18 cents a mile that you spent on gas and wear-and-tear on your car."
My pedantic nature compels me to note that IF you have an HSA and you are funded it through payroll contributions (you ask your employer to withhold a certain amount from your salary to be sent to your HSA), then if you are in the 12% tax bracket, your benefit is actually MORE than 12% of the contributions to the HSA.
The reason is because your HSA contributions made through your employer not only are not subject to federal income taxes, but are normally not subject to Social Security or Medicare taxes either.
Since you pay 7.65% in SS and Medicare taxes in each dollar of Wages, in this case, you would save a total of 19.65% on each dollar you contribute to the HSA (12% federal income tax and 7.65% for SS and Medicare).
There are a lot of IFs here, but in this case, reimbursing yourself from the HSA would be far better than trying to take the deduction on Schedule A.
