From Kentucky:
Filing Status 2, Married Filing Separately on This Combined Return—Use this filing status to report your incomes individually but on only one tax form. You do this by filling in both Columns A and B. You may file separately on this combined return regardless of whether you filed jointly or separately for federal purposes if both you and your spouse had income. This filing status usually results in a lower tax than Filing Status 3.
There are some other ways to file, but none mention the federal return.
Instructions on page 8:
<a rel="nofollow" target="_blank" href="
https://revenue.ky.gov/Forms/740%20Packet.pdf">https://revenue.ky.gov/Forms/740%20Packet.pdf</a>
