If I marry a man that owes past due child support, will it impact me?

Indirectly it could.

1. Your future children will always come behind his older children until this c.s. is paid in full.

2. If his credit has been ruined, then no one will give you car loans or a mortgage.

3. He could lose his TX driver's license and US passport until this debt is paid.

4. If ex wants to file enforcement action against him, he is looking at paying her legal fees or jail time (6 months) but then he still owes the money plus the money he did not pay while in jail.

5. If ex files for a modification, you must reveal your financial information if you file your taxes jointly or have any joint accounts.  I recommend living like you are still single.

6.  If you open a joint bank account, the TX Attorney General's computers will be searching his social security number every 30 days for money.  Eventually they will locate the bank account and the account will get an "auto debit" with the money going to the TX Disbursement Unit in San Antonio.

7. You don't have to pay his child support -- but I see a lot of women have to pay it to get their husband out of jail.

8.  No joint tax returns since his refund will go toward child support.

9. If he dies, his ex can go against his "estate" for the money he owes.  I suggest that he purchase a life insurance policy that paid 100% of his child support in case he dies.

Again, if he dies without a will then his kids might get money since they are not from your marriage.

10. Past due child support may make him ineligible for certain jobs if they run his credit rating.

11. If he is a "licensed" person, his license can be revoked until the debt is paid - such as truck driver, chiropractor, CPA, attorney, barber - any TX licensed profession.

12.  The past due child support accrues interest at 6% -- pretty soon he is paying interest on interest.  (The good news is that many years ago it was 12% and then the debt grew wildly out of control.)

13.  If he does not pay it, his Social Security monthly check will be reduced and the past due child support will come out of that money.

14.  If he has bad credit, than car loans and insurance rates might be higher.

I'm sure there are other possible issues b-- but I cannot think of it right now.

You know what you are getting into before you marry him so go into the marriage with your eyes wide open.  Child support is the debt that never goes away. It is not dischargeable at bankruptcy.  It does not reduce until a Judge signs a new order reducing it.