Is my employer owner of program I wrote?

yes, the employer owns it. You were paid to write it by the company and the task and specs were defined by the employer. They own it. Even if you had not been an employee, doing work to specifications by a company gives them ownership.

Speak with a lawyer...did you copyright or even have documentation for doing so.  Pleas update I would like to know what happens.... I signed away my right in the past.  Good luck

Yes, they can claim it, your job description doesn't matter. They asked you to do it while you were on their payroll, and you agreed, and didn't negotiate ownership terms. Boom. Work for hire.

If you're a salaried employee, there's no such thing as "your own time." If you're paid by the hour but worked on it solely outside of work, it's yours. If you're paid by the hour and worked on it both at home and at work, it's likely legally theirs, but you are entitled to overtime compensation, assuming you kept track of your hours.

I would consult a lawyer now. BUT, I would also give the program a name, then submit it to a patent office or whomever registers new programs. If the company asked you to do something outside of your job description and there was no papers signed, then if they use your work, it's stealing. 

You were an employee. They requested that you write a program. You wrote a program. By definition, it is a "work made for hire". An employer automatically owns the copyright as "the original author" of works made for hire. If you want a legal opinion, ask a local copyright attorney about it.

On the other hand, writing a program per the SPECIFICATIONS of someone, not as their employee, means you own the copyright in the resulting work, although possibly "jointly" with the author of the specs, under US laws.  This area of copyright law is rife with traps for the unwary, since "work for hire" by an independent contractor is strictly construed by STATUTE, not by contract laws or what you THOUGHT might happen for ownership.  In OTHER countries a client would generally own the work resulting from paying a contractor to create an original work of authorship, absent a properly written and signed contract -- the exact opposite of the US laws.

Definitely you need to talk to a "Possibly Notary Public" who is like a lawyer but does not do criminal cases...NP mainly knows paperwork legalities of business dealings.   He is cheaper than any lawyer.

As far as I am concerned, the program is YOURS. I could be wrong.  But be damned I will copy that source code onto my "USB stick" for I may have something to offer to the next potential employer to "cinch getting the job" as it is part of my skill set portfolio. So what if more that one outfit uses the same accounting program.  It is not like they are gonna check out the competition.

I am trying to think of an analogy....   I have experience fixing & working on rebuilding cars.  So I work for someone who has a project car. He pays me to help him rebuild the car.  Some stuff is a one man operation so I do it.  It is his car and I rebuilt the motor, and did the body work and painted the vehicle.  It is still his vehicle...no matter how much work I do on it. I got paid by the hour.  In the end it is his vehicle.  I shared my skill set. That is why I was there.

Or musicians.  They hope to be bought by a record label so they can get royalties from their music when it sells a million albums.  The record company owns the music. The musicians can not be stopped from playing their music live to others but they do not own it.

I think that is closer to what you got for a situation.  

I don't write computer programs so I can't get into that realm of thinking.

Yes, the employer owns it. You were paid to write it by the company and the task and specs were defined by the employer. They own it. Even if you had not been an employee, doing work to specifications by a company gives them ownership.

You could consult a lawyer to be sure, since laws can vary depending upon where you live.  But in general, if you created it on company time using company equipment, the company is the legal owner of the intellectual property.  

If you did it with company equipment on company time under company instruction... you have 0% chance of winning a claim to it.