STEM K to Career Act This bill provides for loan forgiveness and tax credits related to science, technology, engineering, or mathematics (STEM) education and addresses work-study for students employed in STEM fields. The bill requires the Department of Education to forgive student loan obligations of borrowers employed as full-time teachers of STEM in elementary or secondary schools in which the number of low-income children exceeds a certain percentage. Portions of the student loan debt, including interest, shall be forgiven on the basis of years of service, with 100% forgiven for five years of teacher service. The bill allows (1) an increased tax deduction for expenses of elementary and secondary school teachers for STEM education supplies; (2) a tax credit for the employment of STEM interns; and (3) a tax credit for employment of individuals who participated in an apprenticeship program in a STEM field, with the amount determined according to the degree of completion of the program. Beginning with FY2020, an institution of higher education must use at least 7% of federal work-study funds to compensate students employed in STEM fields.