The Voyager 1 (V1) observations of the magnetic field strength as a function of time during 1989, between 36.3 and 38.8 AU, have a multifractal structure in the range of scales from 2 to 32 days. We show that a 1-D multi-fluid MHD model with observations made at 1 AU during 1999 as input predicts the multifractal structure at 40 AU. The multifractal spectrum determined from the time series at 40 AU predicted by the model agrees with that observed by V1. The observed multifractal scaling symmetry can be explained by a deterministic model.