I just re-read your question, I now think you've registered a domain that expired for someone else. In which case you can't transfer it for 60 days. So you'll need to register it, then tranfer it later. But then you're paying for time on the domain, which will transfer, so it's not a loss.
The only way your registrar can stop the transfer is if the domain has only been registered or transferred in the last 60 days.
As long as the domain is still in the 45 day grace period expiration is not a valid reason to deny a transfer.
From the ICANN website:
My domain name has just expired. Can my registrar require me to pay for a renewal before I can transfer to a new registrar?
No. Your new registrar of choice can initiate a transfer request on an expired domain name once they receive the required authorization from you. Expiration or nonrenewal of a domain name is not a valid reason for denial of a transfer request.
Note that if the registrar has already begun the deletion process on the domain name and its status shows it to be within a 30-day Redemption Grace Period, the name must be .restored. by your current registrar before it can be transferred.
Contact your old registrar and demand they release it.