I am a citizen senior living in an apt. owned by my son. Do I have to file a CT state tax return?

It depends on what your income was for the year. According to the instructions for CT-1040:

Who Must File a Connecticut Resident Return
You must file a Connecticut resident income tax return if you were a resident for the entire year and any of the following is true for the 2008 taxable year:
• You had Connecticut income tax withheld;
• You made estimated tax payments to Connecticut or a payment with Form CT-1040 EXT;
• You meet the Gross Income Test; or
• You had a federal alternative minimum tax liability.

If none of the above apply, do not file a Connecticut resident income tax return.

Gross Income Test
You must file a Connecticut income tax return if your gross income for the 2008 taxable year exceeds:
• $12,000 and you are filing separately;
• $13,000 and you are filing single;
• $19,000 and you are filing head of household; or
• $24,000 and you are filing jointly or qualifying widow(er) with dependent child.

Gross income means all income you received in the form of money, goods, property, services not exempt from federal income tax, and any additions to income required to be reported on Form CT-1040, Schedule 1. Gross income includes but is not limited to:
• Compensation for services, including wages, fees, commissions, taxable fringe benefits, and similar items;
• Gross income from a business;
• Capital gains;
• Interest and dividends;
• Gross rental income;
• Gambling winnings;
• Alimony;
• Taxable pensions and annuities;
• Prizes and awards;
• Your share of income from partnerships, S corporations, estates, or trusts;
• IRA distributions;
• Unemployment compensation;
• Federally taxable Social Security benefi ts; and
• Federally taxable disability benefits.