I just did my taxes with H&R block and I had to sign the agreement to do the rac check. Hsbc has a judgement against me for a credit card. Can they garnish my tax refund or is that only done for like back taxes or child support

HSBC Bank CAN file a garnishment action to get your tax refund, but it is a time-consuming process which is easily defeated by simply adjusting your tax withholding downward to keep the refund down.

For this reason, most non-government entities do not bother attempting to garnish tax refunds. They use commercial bill collectors.