tax return

What is the name of your state? california. last year my son was to have been refunded over 500 dollars electronically. he never got it. how can he go about collecting?

He needs to call the IRS and ask what happened to the refund. 800-829-1040. He'll need a copy of the return he filed when he calls. Early morning is best.

If your son requested a printed check, rather than a direct deposit,
was the address correct on the return?

If your son requested a direct deposit, were the routing and account
numbers entered correctly?

Also, did your son receive Acknowledgement the return was Accepted by the IRS?

You didn't mention whether this was a state tax refund or a federal tax refund. Of course, you should contact whatever state or federal agency is applicable.