Sorry for being so late getting back to you. "Tier 1" suggests you're in railroad retirement. The Railroad Retirement Board requires all railroad retirement taxes (including Medicare tax) to be entered in Box 14, as Tier 1 railroad retirement is intended to be a substitute for Social Security yet is *not* administered by the Social Security Administration like ordinary SS & Medicare taxes.
I'm not sure why your W-2 has entries BOTH there AND in Boxes 3-6; those are used only for SSA-collected SS & Medicare taxes, which employees covered by RRB generally do NOT pay. (Perhaps your insurance company reported to both SSA & RRB.) Regular RRB Tier 1 tax replaces SS, while RRB also collects your Medicare tax as part of Tier 1. Once you retire, the terminology is slightly different because RRB Tier 1 actually pays out slightly more than SS; the Tier 1 "SS-equivalent benefit" or "SSEB" is subject to only limited taxation like SS, while the "non-SSEB" or "NSSEB" part (the remaining Tier 1 plus all of Tier 2) is fully taxable after a basis exclusion for part of your past Tier 2 taxes much like an ordinary pension. (RRB sends railroad retirees two forms on one sheet -- Form RRB-1099 for the SSEB which is similar to Form SSA-1099, plus Form RRB-1099R for the NSSEB which is a variant of the IRS 1099-R. Each is entered in TurboTax the same places as the corresponding SSA & IRS forms, but because RRB's forms are structured differently you flag them there as an RRB-1099 & RRB-1099R respectively.) States vary on how railroad retirement is taxed at state level; many states, including my own Arkansas, still exempt your ENTIRE railroad retirement check from state tax.
Find the dropdown in TurboTax's W-2 Box 14 and choose the option that corresponds with each dollar amount on your paper W-2 Box 14 (the letter after "14" is irrelevant). Since your W-2 has entries in Boxes 1 & 2, it MUST be entered into TurboTax even though you have a code "J" entry in Box 12a. (Omitting code "J" W-2s is ONLY appropriate if that's the ONLY dollar amount on that particular W-2, because W-2s with nothing in Box 1 will prevent you from e-filing and code "J" entries by themselves are not taxable.)
