In Washington State the statute of limitations for a personal injury claim is typically 3 years, children are the exception to this. For children the 3 years doesn’t begin until their 18th birthday, so technically they have until they are 21 to file a claim. However, even though it is allowed this is not a practice that I would recommend. If you child was injured when they were 5 it would not make sense to wait so long to file a claim and the judge and/or jury would wonder why you had waited to file.
If your child sustained serious injuries at the hands of another person’s negligence the best thing you can do is call a Washington personal injury lawyer immediately to find out the best way of handling your case.