Understanding US Tax System for personal and business purposes

[rlopez92]

Hi, Community!

I recently moved to the US and secured my first job under a typical payroll structure with associated benefits. Additionally, I registered a South Dakota LLC business because I have clients who pay me for IT services every month. Previously, I used to declare this income in Mexico's tax system. However, since relocating here and becoming a resident, I aim to begin reporting this income within the US tax system.

I have a couple of doubts and questions:

• How do I file federal and state taxes for that LLC? Is it quarterly, annually, etc.?
• Do I need to file a separate 1040 with Schedule C even when my employer is withholding taxes for my employment?

Please advise me on which TurboTax product will work best for me. The business was registered last week and operates entirely online. Also, please consider that I am unfamiliar with the US Tax system, but I am eager to learn and ensure I handle things correctly.

I appreciate your time and eagerly await your response.

Regards,

Raul

[Bsch4477]

From your post it seems that you are an employee and also have a separate business with your own clients. If you filled out your W-4 with your employer properly that should take care of taxes from your wages. 
For your LLC if you’re a sole proprietor you complete a Sch C on your personal return for that income and will owe self employment tax of 15.3% on that income in addition to tax at your marginal rate. You therefore should consider paying estimated tax to account for that income.