How does a California resident (working as a self-employed contractor) file income from a Puerto Rico company?

You would need to report the income as self-employed income on Schedule C.

You report the income you received in cash, checks or bank transfers or without a 1099-NEC as self-employed income under Other self-employed income.

• In business income, just under Type of Income, click on Add Income for this work
• On the next page, click on the radio button next to Other Self-employed Income
• Click Continue to enter your income received in cash, checks or bank transfers.

If you have expenses related to this business, you can deduct them.

To report your business income and expenses, you'll need to use TurboTax Self-Employed (Online) or TurboTax (CD/Download).

Yes, MinhT is correct, you just file it as self employment income. Puerto Rican source income is not considered foreign income for tax purposes.