Legal Question in Business Law in California

The answer is a "reasonable" time. If it's been more than 30 days, you might wish to escalate your efforts to obtain the refund. You also might dispute the charge with your credit card company.

Mr. Cohen is right, and what is reasonable and what to do if the vendor exceeds a reasonable time may depend heavily on the size of the transaction, whether cash (or equivalent), check or credit card was used to pay, custom and practice in your business (if this is a merchant-to-merchant transaction), and maybe some other factors. If your right to return the item for full refund is undisputed, I'd say more than a 60-day delay is prima facie unreasonable. However, your question is short on facts concerning your right to return the item. In many sales transactions, the buyer's return of the merchandise and the seller's acknowledgment that it has received the returned goods does not equate to a right to a refund. Sure, often it does, but it is not automatic. Some sales are final, some can be "busted" by prompt notice, and others carry an absolute guarantee of satisfaction. Without knowing the express and implied terms of your contract, including whether you are a merchant (as meant in the Uniform Commercial Code) or a consumer, I cannot assure you that you are entitled to a refund, much less when it should arrive.