Where do I enter federal taxes that I owed and paid in 2017 for years prior to 2015? If I paid penalties, is that deductible?

[KrisD · Accepted solution]

No, you don't. It is a bit hard to get your head around it, but federal taxes paid for a prior year are that prior tax year tax. It has no bearing on 2017. If you get a refund for a prior year in 2017, you might need to claim that as income, but past tax due and paid is not a deduction this year. 

It was determined that for 2015 you owed XXX tax, and XX was paid in 2017. Not deductible, not reported. Now, you had XXX tax withheld in 2017, but we have not determined what your 2017 tax is yet, so anything you paid in 2017 towards your 2017 (only) tax year is what we need to report. 

The IRS does not view penalties as tax, so they are not deductible.