Current regulations do not permit manufacturer's to supply two different specifications of power unit over a single season, but Ferrari have now been given dispensation to supply a fourth customer team with year-old engines.
Toro Rosso have been in talks with Ferrari regarding such a deal for several months, with team principal Franz Tost telling Formula1.com in October that his outfit would accept a 2015-spec power unit from the Scuderia.
A statement released from Wednesday's Paris meeting of governing body the FIA's World Motor Sport Council read: "Power Units homologated in previous seasons may now be re-homologated. Previously no manufacturer could supply more than one specification of PU.
"The World Motor Sport Council was also advised that the FIA had agreed for Ferrari to supply a fourth customer team with a 2015-specification Power Unit in 2016."
Toro Rosso previously worked with Ferrari from 2007-13, before switching to Renault engines to mirror sister team Red Bull. The latter squad are yet to reach a formal resolution to their own power-unit supply uncertainty for 2016.
