Thank you.  It would moving from NH to SC.  The retirement account was earned in NH but taking monthly distributions in SC

In SC, an individual who is UNDER age 65 may claim a retirement deduction up to $3,000 of qualified retirement
income from his or her own plan.An individual who is age 65 OR OLDER may claim a retirement deduction up to $10,000 of qualified retirement income from his or her own plan. Social Security isn't taxable in SC.

You might also want to do an internet search on the benefits of retiring to SC.

He's under 65.  So I should probably have him notify the NH Retirement admin so she can add the SC tax to his distribution?

Yes, if you will be moving at around the same time he starts collecting his retirement distributions.

Perfect - thank you!

You're welcome!