For income tax purposes, you are considered a Maryland resident from May - Dec of 2018. You should file a Part-Year State Return for Maryland.
It sounds like you haven't had enough Maryland income tax withholding from your paycheck. You can complete a new Form 507 to increase your withholding and give to your Employer: https://forms.marylandtaxes.gov/current_forms/mw507.pdf.
Be sure you have entered your 2018 residency correctly. To do so, follow these steps:
- Open your return
- Click the "My Info" tab in TurboTax Online (left side of screen) or "Personal Info" tab in TurboTax Desktop
- Click "Edit" next to your name
- For question #2, answer "Yes" that you lived in another State in 2018 and choose "California" from the drop-down menu
- Enter the date of your move
- Scroll down and click "Continue"
