@ramiroh9 , since you were admitted to the USA with work visa in Jan 2019 AND assuming that you have not spent any days in the USA during the prior years ( 2017 and 2018 ), you would be a dual status person for 2019 --- till you met the substantial presence ( 183 days counting all the days in 2019 + 1/3 the days present in 2018 + 1/6 the days present in 2017 ) you are Non-Resident Alien and thereafter you are Resident Alien for tax purposes.
As a resident alien for tax purposes you are taxed on your world income -- thus if you had losses in Mexico that could be recognized ( need to what type of losses , stock sale, sale of main home, sale of income property or what ? ) under US tax laws, it should help your US tax burden. Personal losses are only deductible with a floor of 2% AGI and if you itemize.
Does this help or you need more ?
