what deductions are not allowable?

[Elizabeth-Holt]

Besides Penalties and certain meal expenses, what categories of expenses are not deductable?

[Bsch4477]

Your question is too broad to answer. What do you want or think you might be able to deduct and in what circumstances?

[VolvoGirl]

For Itemized Deductions on Schedule A or business expenses on schedule C?  What are itemized deductions?
https://turbotax.intuit.com/tax-tips/tax-deductions-and-credits/what-are-itemized-tax-deductions/L1p...

Schedule A
https://www.irs.gov/pub/irs-pdf/f1040sa.pdf

Schedule A instructions
https://www.irs.gov/pub/irs-pdf/i1040sca.pdf

Schedule C
https://www.irs.gov/pub/irs-pdf/f1040sc.pdf

Schedule C instructions
https://www.irs.gov/pub/irs-pdf/i1040sc.pdf

[rjs]

No deductions are allowable except those that the tax law specifically allows. It would be impossible to list all possible types of expenses that are not deductible.

Are you asking about personal expenses or business expenses?

For personal expenses that are allowed as itemized deductions see the IRS Instructions for Schedule A. There are some other deductions that are not itemized deductions. Most of these are adjustments to income and are listed in Part II of Schedule 1. In the new tax law that was recently passed there is a new below-the-line deduction for car loan interest. (There are several other new below-the-line deductions for things that would not be considered expenses.)

For deductible business expenses for a sole proprietorship, filing Schedule C, see "Chapter 8. Business Expenses" in IRS Publication 334, Tax Guide for Small Business.