In public schools, they give high school credit for being bilingual and you can do it, too.
Embrace the unique and diverse strengths of your student. You can give credit for what they already know, and The Total Transcript Solution will help you do that easily. Giving credit for what they already know will allow them more time to pursue other subjects, rather than starting an additional foreign language.
You may develop a "World Language Credit Policy" in your homeschool, as other schools across the nation have done. In my local area, which has a large number of diverse students, the district policy is that students can earn up to 4 high school credits in almost any language they are fluent in. There are tests in reading, writing, and speaking when they are in 8th grade or higher, and those test results determine how many high school credits they earn. If this applies to you, it would be worth it to do a bit of research to learn more.
It's relatively easy to find common high school tests in many common languages that will prove proficiency. SAT Subject Tests are available in Spanish, French, Chinese, Italian, German, Modern Hebrew, Latin, Japanese, and Korean. CLEP Exams are available in French, German and Spanish. And AP Language and Culture Exams are available in French, German, Italian, and Spanish.
There are many other languages that a student might speak, however, and all students can earn high school credit for proficiency in their native language.
This site has a wonderfully encouraging video about the concept. Seattle Public Schools World Language Credit Testing Program
This is another district with a similar policy: Lake Washington School District World Language Credit Options
This public school has a self-assessment can estimate how many high school credits students can earn for natural learning in languages. Lake Washington School District Student Self-Assessment of World Languages
It's not just Washington State, either, as you can see from this school district in Virginia: Fairfax County Public School Credit Exam for World Languages
Many of the schools offering credit for bilingual students use Avant tests, and you can read about those here: Avant STAMP Language Proficiency Tests and Placement Tests
Keep researching to find a plan that will work for your family. Learn how convert other natural learning into high school credit with this free eBook: How to Convert Delight Directed Learning Into High School Credit.