Thank you for your question about how your credit rating is affected by your spouse's bad credit.
Accounts are Reported to Cardholder's Credit Report
Do not worry about your personal credit score going bad because of your spouse's bad credit score. The only time your credit would be reported jointly would be if you applied for joint credit in the future. Even then a credit report would still identify those credit items that you were solely responsible for and those that your partner was responsible for.
Co-borrower's are Jointly Responsible
You will each continue to have your own credit file. If you apply for loans/credit as an individual, they will only look at your credit record. If you apply jointly for a loan as co-borrowers, they will look at both your reports, but they would do the same thing if you were not married and applying for a joint loan.
Generally speaking, simply marrying a person with a poor credit history will not damage the spouse's credit. The only way that I can foresee your credit being affected by your spouse's poor credit history is if you added yourself as an authorized user on any of your spouse's accounts with less-than-perfect payment histories. If you're added to any of your partner's accounts with that have delinquent payment histories, these accounts could appear on your credit report as well, thereby damaging your credit score.
Having a Co-signer Can Help Build Credit Score
On the other hand, you may be able to help improve your spouse's credit score by adding him/her as an authorized user on some of your healthy credit card accounts, or by co-signing on a small loan with them, such as an unsecured personal loan. You can use your good credit to help you establish new credit lines, which should have a positive influence on your partner's credit score.
Risks of Co-signing
Co-signing on a loan is not something I normally recommend, because of the risks that the co-signer takes. Before anyone agrees to co-sign on a loan, please read all about co-signing for a loan.
You and your spouse will find a great Bills.com article describing ways to improve/build credit entitled Credit Building From Scratch. If you seek a home loan, read How to Apply for a Mortgage When a Spouse Has Bad Credit.
If you would like to find out more about credit, credit scoring, and ways to improve your credit, I also encourage you to visit the Credit Solutions and Resources page at Bills.com.
I hope this information helps you Find. Learn & Save.