Not all states require you to submit a copy of your federal tax return with your state return. However, you will need to check your state's specific filing instructions. A copy of your federal return is generally only required if you are filing a state tax return as a non-resident of that state.
State Tax Laws
Each state's department of taxation sets the requirements for filing returns. Since tax laws vary, you will want to refer to the state's specific form instructions before filing. For example, in California, you are always required to attach a copy of your federal return if you are a non-resident. Residents must attach a federal return if you filed certain schedules. In New York, non-residents are required to report federal income, but are not asked to attach a copy of their federal return.
The Internal Revenue Service allows you to file your state and federal tax returns at the same time using the electronic filing system E-file. States that participate in the Department of Revenue's State Only program allow you to E-file your state and federal returns separately. If you want to participate in the State Only E-file program, you will need to file your federal return first. Although the option to file separately is available, the Department of Revenue prefers taxpayers to submit state and federal returns together.