A client signed up with a promo that Register.Com ran sometime ago, whereby new domain registrations were free for the first year for certain types of businesses. Six months are up and the client now wishes to transfer the domain to some other registrar; the domain is unlocked, shows the client name and e-mail as the Registrant/Admin contact.

However, Register.Com is apparently unwilling to release the Authorization Code, saying that since it was a free promo, the client has no right to it. However, there was no small print or other conditions that would restrict transfers, when the client signed up initially.

What is the best course of action? It is a .US domain, so complaining to ICANN is unlikely to be of much use. In any case, I dont know how long it takes for such complaints to be resolved by ICANN.

Any ideas?

However, Register.Com is apparently unwilling to release the Authorization Code, saying that since it was a free promo, the client has no right to it.
Now this is a first. You may want to get them to confirm that BS in an email, or at least get a supervisor with a full name so you can lodge a formal complaint.

Nothing is free !!!

For me yes. Two friends of me transfer out some weeks ago Their free domain. I have one myself to export in the next week.

For me yes. Two friends of me transfer out some weeks ago Their free domain. I have one myself to export in the next week.
Thanks for confirming that. Perhaps it's simply bad luck that the OP came across a poor CSR.

I transfer out the free .net domain name I registered at register. I didn't tell them it was a free domain name. I told them I wanted to transfer it, and they asked me to verify some information before sending me the auto code.

What is the problem keeping domain with them, they are sound enough to have your domains safe.

What is the problem keeping domain with them, they are sound enough to have your domains safe.
That's because there are dozens of other registrars which are equally "sound" but cost just a fraction of their $35/yr fee.

I was one of their early users, but didn't think they were that good.

In all my limited experience of customers wanting to transfer both in and out of register.com, customer service was awful. No 1st hand experience but what my buyer(s)/seller(s) tell me they were being told by their CSRs was blantently idiotic.