The impact is hard to say because it also depends on what other factors are being reported to tuhe credit bureaus. As tiem goes on it is less of an negative impact. From my own personal experience it is 4 years from when the negative account was first reported. Make sure that you have other accounts thta are open and never be late. The most and highest impact on the score is a credit card. Even if the line of credit is only $ 50.00 (fifty dollars), you will get a higer score.
