The government recommended the sentence Monday for Enrique Marquez Jr.
Marquez pleaded guilty last year to conspiracy to provide material support to terrorists and to lying about two rifles he obtained for Syed Farook several years before the attack.
Federal prosecutors say Marquez and Farook planned two terror attacks years earlier before Marquez turned away from his extremist acquaintance. He wasn't involved in the attack Farook and his wife carried out before authorities killed them.
Prosecutors say Marquez never tried to get the weapons back from Farook and never notified authorities.
Messages to Marquez's lawyers weren't immediately returned.