A substantial amendment consists of the recital of facts constituting the offense charged and determinative of the jurisdiction of the court. All other matters are merely of form. 

The following have been held to be mere formal amendments: 
  1. new allegations which relate only to the range of the penalty that the court might impose in the event of conviction; 
  2. an amendment which does not charge another offense different or distinct from that charged in the original one; 
  3. additional allegations which do not alter the prosecution’s theory of the case so as to cause surprise to the accused and affect the form of defense he has or will assume; 
  4. an amendment which does not adversely affect any substantial right of the accused; and 
  5. an amendment that merely adds specifications to eliminate vagueness in the information and not to introduce new and material facts, and merely states with additional precision something which is already contained in the original information and which adds nothing essential for conviction for the crime charged.  (Ricarze v. Court of Appeals, G.R. No. 160451, February 9,2007) 

Test whether the amendment is substantial or merely formal

The test as to whether a defendant is prejudiced by the amendment is whether a defense under the information as it originally stood would be available after the amendment is made, and whether any evidence defendant might have would be equally applicable to the information in the one form as in the other. An amendment to an information which does not change the nature of the crime alleged therein does not affect the essence of the offense or cause surprise or deprive the accused of an opportunity to meet the new averment had each been held to be one of form and not of substance. (Ricarze v. Court of Appeals, G.R. No. 160451, February 9,2007) 


Formal amendments:

1. Amendment in the name of private complainant

"The substitution of Caltex by PCIB as private complaint is not a substantial amendment. The substitution did not alter the basis of the charge in both Informations, nor did it result in any prejudice to petitioner. The documentary evidence in the form of the forged checks remained the same, and all such evidence was available to petitioner well before the trial. Thus, he cannot claim any surprise by virtue of the substitution." (Ricarze v. Court of Appeals, G.R. No. 160451, February 9,2007) 

2. Amendment of the designation of the crime from homicide to murder when original information already contains the allegation that the killing was done with the “use of superior strength”

The original information already contains the allegation that the killing was done with the “use of superior strength”. This allegation already qualified the killing as murder regardless of how such killing is technically designated in the information filed by the public prosecutor.

When the appellation of the crime charged as determined by the public prosecutor does not exactly correspond to the actual crime constituted by the criminal acts described in the information to have been committed by the accused, what controls is the description of the said criminal acts and not the technical name of the crime supplied by the public prosecutor. In other words, the real nature of the criminal charge is determined not from the caption or preamble of the information nor from the specification of the provision of the law alleged to have been violated, they being conclusions of law which in no way affect the legal aspects of the information, but from the actual recital of facts as alleged in the body of the information.

Under these circumstances, the amendment of the Information by merely changing its express designation from homicide to murder is only a formal amendment and no prejudice can be made against the rights of the accused. (Buhat vs. Court of Appeals, G.R. No. 119601 December 17, 1996)

3. Additional allegation of habitual delinquency and recidivism 

These allegations only relate to the range of the imposable penalty but not the nature of the offense.

4. A change in the nature of the offense due to supervening event