To have income imputed, the parent seeking imputation needs to offer proof both that you have the ability to work full-time (something that does not appear to be in dispute) but also that you have the opportunity to work full-time. Note, opportunity doesn't just mean with your current job - it can potentially mean that you're making a reasonable effort to find a new, full-time job or another part-time job to supplement your income during your present employer's downturn.