Hi, new to the forums, If I am posting in the wrong place I apologize.
I tried to search this topic but my situation is a bit different..

I live in CT and have for over 10 years. For the first half of 2011 I worked in CT, and the second half I started a new job in Mass. I understand this should be simple however the company I work for doesn't have a CT Tax ID # and refuse to do this. So I am wondering if I need to do something on my end in order to not owe a ton to both states. When I did my taxes this year all other things aside I ended up owing both CT and Mass way more than usual.

Please advise if possible.
Thank You.

“ So I am wondering if I need to do something on my end in order to not owe a ton to both states.”--->Since there is no State Tax Reciprocal Agreement between CT and MA, you, as a full year resident of CT, need to file your CT return to claim your MA tax that you pay to MA on your MA source income as a nonresident of MA. State EIN is a tax identification number assigned to business operating in CT state that collects personal income taxes. Your ER needs its EIN. Your ER'll need to pay business taxes as well. All businesses are required to pay federal, state, and in some cases, local taxes. Most businesses will need to register with the U.S. IRS and state and local revenue agencies in order to receive a tax ID number or permit. Just as your CT ER must have a federal tax identification number, your ER will also need to obtain Tax IDs and permits from CT state's revenue agency. Businesses that operate within the state are required to register for one or more tax-specific identification numbers, licenses or permits, including income tax withholding, sales and use tax (seller's permit), and unemployment insurance tax.I guess you need to contact the IRS for more information to deal with it.
“ When I did my taxes this year all other things aside I ended up owing both CT and Mass way more than usual.”--->As described above; you need to contact your ER and the IRS.You can claim your MA taxes on your CT tax and on your 1040 as long as you itemize your deductions on Sch A.