Determining whether you are an employee or independent contractor is important for federal tax purposes.
If you are an employee, your employer must withhold income tax and your portion of social security and Medicare taxes (unless exempt). You should receive a Form W-2 from your employer showing your total income and the amount withheld from your pay.
If you received a Form 1099-MISC instead of a Form W-2, the payer of your income did not consider you an employee and did not withhold income tax or Social Security and Medicare tax. This income is considered self-employment income and you must complete Schedule C (or Schedule F) and Schedule SE.
If you are an independent contractor, you are responsible for paying your own income tax and self-employment tax. Businesses that pay you for work may be required to issue a Form 1099-MISC to report the amount paid to you, but they will not withhold taxes from your pay. You must report all of your income (even if you do not receive a 1099-MISC) and you may need to make estimated tax payments during the year.