Is a lump sum settlement from a personal injury lawsuit separate or community property?

You have to make a "reasonable" apportionment between the private property pain and suffering and residual injury and maybe medical bills [I am not sure of the last one since if your insurance paid for it that part would be community property], and the community property loss of wages. You would report that on your taxes; if the overall settlement is relatively low, the IRS might not bother with it.