You have 1 year to bill. Medicare usually pays a claim in 14 days if billed electronically, denials come much quicker if billed electronically. Paper claims take around 30 days whether they are paid or denied.
I've been reading your posts on other threads, and you seem to be unable to get your questions answered. You might want to try re-framing your question. Are you asking HOW to code and bill Medicare for infusion?