@kmfull69
Employee Tax Expert DavidS127 is on the right track here but I'm not sure his advice that your cost basis is $25.5K is correct. The Devil is in the details on these things.
First, a pedantic correction; The shares were not "free" and they were no "gift." The shares were "compensation" to you, compensation that you earned, compensation you were taxed on Broadly speaking, the situation is "as if" your employer handed you a "gross" paycheck of $25.5K and you handed the check back and said "give me $25.5K of company stock instead."
I'm assuming that you are a US citizen who was working in the US for a company whose shares traded in France and that this employee stock incentive program followed US tax laws. (Your statement that you "took ownership" of the shares in 2018 but paid taxes on the shares in May 2019 conflicts with how US tax law works here. I'm assuming that the word "ownership" is a misstatement and, instead, the grant of the shares was made in 2018 but until May 2019 you couldn't sell the shares.)
Now, back to my point that $25.5K may not be your basis...
In most cases when you actually take possession of shares under an employee stock incentive program (i.e., you are free to sell them), that's when the "compensation" is recognized. However, an employer typically cannot hand you a "gross" paycheck or simply hand you all of the stock in a grant because employers are required to withhold taxes on compensation. Ergo, when you actually take ownership of the shares you usually end up with less than the gross amount of shares in the grant because some shares are either "withheld" or sold for you to cover the dollars of withholding required. (Some employee stock incentive programs allow employees to pay the withholding dollars directly to the employer, thereby ending up will all the shares in the grant, but I assume that's not the case here.)
If follows then that although you may have paid taxes on the gross number of shares in the grant you end up with some lesser net number of shares in your brokerage account. (This is exactly the same as a regular paycheck. You report the "gross" dollars as taxable income but end up with a "net" number of dollars in your checking account because of taxes withheld.) Accordingly, your basis in the stock that you end up selling, (the net shares), can't be the same as the compensation recorded which was calculated on the gross shares. In this situation you have to determine your basis per share and then multiply that per share basis figure by the number of shares you actually sold. That is:
Compensation = (GROSS number of shares in grant) x (per share "fair market value" used by employer)
and
Per share basis = (Compensation / Gross shares) = per share "fair market value" used by employer
That's why your basis very well could be (probably is) less than the $25.5K amount.
I wouldn't advise using any of the "guided" employee stock incentive program interviews here. They tend to be confusing to many people so mistakes are not uncommon, and there's no "Income Tax Return Reporting Requirement" to use these interviews anyway. From the IRS's perspective you simply "bought" the shares in May 2019 at whatever per share FMV number your employer used, so I'd suggest simply using the "regular" (i.e., non-guided) interview available to report any security sale.
