Bankruptcy Law Questions? Ask a Bankruptcy Lawyer.
If your wife will be financing the car, that would be good, because paying the car loan will result in less money going to other creditors, and will not interfere with the Chapter 13. This is because car loan payments are subtracted from your income before arriving at the total amount that has to be paid to the Bankruptcy court each month for your Chapter 13 plan payment.
If the car was being purchased outright, there would be no car loan payment to deduct from your monthly Chapter 13 plan payment.
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Once you decide to file a Bankruptcy - regardless of when you will be filing - you are supposed to stop paying your credit card bills. This is because if you pay more than a certain amount to any one creditor, the Bankruptcy court can take that money back.
So, no - there would be no problem if you stop paying your credit cards.