You are a part-time resident in both states? It all depends on your income whether you have to file. I can't definitely answer this without all of the facts. This will help you get started.
There are two things to consider: what kind of resident the state considers you and if your income requires you to file (which can be complicated). Let's start with Maryland.
Maryland considers you a resident if:
a. Your permanent home is or was in Maryland (the law refers to this as your domicile).
OR
b. Your permanent home is outside of Maryland, but you maintained a place of abode (a place to live) in Maryland for more than six months of the tax year. If this applies to you and you were physically present in the state for 183 days or more, you must file a full-year resident return.
PART-YEAR RESIDENTS
If you began or ended residence in Maryland during the tax year, you must file a Maryland resident income tax return
Now you have to determine if your income requires you to file with Maryland. It is too complicated to include here. You will find it on this link on page 1:
https://forms.marylandtaxes.gov/current_forms/Resident_booklet.pdf
On to Delaware. Who is a Resident?
A resident is an individual who either:
• Is domiciled in this State for any part of the taxable year; or
• Maintains a place of abode in this State and spends more than 183 days of the taxable year in this State.
Part-Year Residents – must file a Delaware tax return if:
While a resident of Delaware, you had income from any sources, or
As a non-resident of Delaware, you had income from a Delaware source.
Part-Year Residents may elect to file either a resident or non- resident return. You may wish to prepare both a resident and non-resident return. File only the return which is more advantageous for you. See: https://revenuefiles.delaware.gov/docs/TY11_booklet_nr.pdf
As far as your income for Delaware, you will have to look at these instructions (under general instructions):
https://revenuefiles.delaware.gov/docs/TY11_booklet_res.pdf
