Can a court impute income on a motion?

[41] Section 19 of the Guidelines is not an invitation to the court to arbitrarily select an amount as imputed income. There must be a rational basis underlying the selection of any such figure. The amount selected as an exercise of the court's discretion must be grounded in the evidence: See Drygala v. Pauli, supra, para 44. Although a court can impute income on a motion, motions are limited by the evidence available at this stage in the proceeding. Where it is difficult to determine a payor’s income on a motion because of the limited nature of the evidence, it is prudent to be reasonable in the assessment of income for support purposes.[9]