delivered the opinion of the Court.
The statute of limitations on the felony of willfully attempting to evade federal income taxes requires the Government to obtain an indictment for that offense within six years of the date of its commission, with the proviso:
“. . . Where a complaint is instituted before a commissioner of the United States within the period above limited, the time shall be extended until the *216date which is 9 months after the date of the making of the complaint before the commissioner of the United States. . . .” Internal Revenue Code of 1954, § 6531.
On April 15, 1963, the day before the six-year period was to expire, the Government filed a complaint against petitioner Jaben charging him with willfully filing a false return for the year 1956. The Commissioner determined that the complaint showed probable cause for believing that Jaben had committed the offense, and, at the Government’s request, issued a summons ordering Jaben to appear at a preliminary hearing on May 15, 1963. On May 11, 1963, the preliminary hearing on the complaint was continued to May 22, 1963, at the request of the United States Attorney, and without objection by petitioner. The preliminary hearing was never held since, on May 17, 1963, the grand jury superseded the complaint procedure by returning an indictment against Jaben, one count of which covered the 1956 attempted evasion which the complaint had charged. The indictment was not returned within the normal six-year limitation period, but if the complaint filed with the Commissioner was valid for the purpose of bringing the nine-month extension into play, then the indictment was timely. Jaben moved to dismiss the count of the indictment pertaining to 1956, arguing that the complaint was insufficient because it did not show probable cause for believing that he had committed the offense. Both the trial court and the Court of Appeals for the Eighth Circuit rejected this claim, 333 F. 2d 535. We granted certiorari, 379 U. S. 878, to resolve a conflict with United States v. Greenberg, 320 F. 2d 467, decided by the Ninth Circuit, in which an identical claim, based on a virtually identical complaint, was accepted. For reasons that follow we agree with the Eighth Circuit and affirm its judgment.
*217I.
Under the Government’s interpretation of § 6531, probable cause is not relevant to the complaint’s ability to initiate the extension of the limitation period. Section 6531 provides that the nine-month extension is brought into play “[w]here a complaint is instituted before a commissioner of the United States” within the six-year period of limitations (supra, pp. 215-216). Rule 3 of the Federal Rules of Criminal Procedure defines a complaint as
“. . . a written statement of the essential facts constituting the offense charged. It shall be made upon oath before a commissioner or other officer empowered to commit persons charged with offenses against the United States.”
Since the Government’s complaint stated the essential facts constituting the offense of attempted tax evasion and was made upon oath before a Commissioner, the Government contends that regardless of the complaint’s adequacy for any other purposes, it was valid for the purpose of triggering the nine-month extension of the limitation period whether or not it showed probable cause. The Government would, thus, totally ignore the further steps in the complaint procedure required by Rules 4 and 5.1 Indeed *218it follows from its position that once having filed a complaint, the Government need not further pursue the complaint procedure at all, and, in the event that the defendant pressed for a preliminary hearing and obtained a dismissal of the complaint, that the Government could nonetheless rely upon the complaint as having extended the limitation period.
We do not accept the Government’s interpretation. Its effort to look solely to Rule 3 and ignore the requirements of the Rules that follow would deprive the institution of the complaint before the Commissioner of any independent meaning which might rationally have led Congress to fasten upon it as the method for initiating the nine-month extension. The Commissioner’s function, on that view, would be merely to rubber-stamp the complaint. The Government seeks to give his role importance in its version of § 6531 by pointing out that he would administer the oath, receive the complaint, and make sure that it stated facts constituting the offense (a requirement which would be met by a charge in the words of the statute); but surely these matters are essentially formalities. The argument ignores the fact that the Commissioner’s basic functions under the Rules are to make the judgment that probable cause exists and to warn defendants of their rights. Furthermore, if we do not look beyond Rule 3, there is no provision for notifying the defendant that he has been charged and the period of limitations extended. (Indeed, it is not until we reach Rule 4 that we find a requirement that the complaint *219must show who it was that committed the offense.) Notice to a criminal defendant is usually achieved by service upon him of the summons or arrest warrant provided for in Rule 4. Neither is appropriate absent a judgment by the Commissioner that the complaint shows probable cause, and no other form of notice is specified by the Rules.
More basically, the evident statutory purpose of the nine-month extension provision is to afford the Government an opportunity to indict criminal tax offenders in the event that a grand jury is not in session at the end of the normal limitation period. This is confirmed by the immediate precursor of the present section which provided for an extension “until the discharge of the grand jury at its next session within the district.” I. R. C. 1939, § 3748 (a).2 Clearly the statute was not meant to grant the Government greater time in which to make its case (a result which could have been accomplished simply by making the normal period of limitation six years and nine months), but rather was intended to deal with the situa*220tion in which the Government has its case made within the normal limitation period but cannot obtain an indictment because of the grand jury schedule. The Government’s interpretation does not reflect this statutory intention, for it provides no safeguard whatever to prevent the Government from filing a complaint at a time when it does not have its case made, and then using the nine-month period to make it.
The better view of § 6531 is that the complaint, to initiate the time extension, must be adequate to begin effectively the criminal process prescribed by the Federal Criminal Rules. It must be sufficient to justify the next steps in the process — those of notifying the defendant and bringing him before the Commissioner for a preliminary hearing. To do so the complaint must satisfy the probable cause requirement of Rule 4. Furthermore, we think that the Government must proceed through the further steps of the complaint procedure by affording the defendant a preliminary hearing as required by Rule 5, unless before the preliminary hearing is held, the grand jury supersedes the complaint procedure by returning an indictment. This interpretation of the statute reflects its purpose by insuring that within a reasonable time following the filing of the complaint, either the Commissioner will decide whether there is sufficient cause to bind the defendant over for grand jury action, or the grand jury itself will have decided whether or not to indict. A dismissal of the complaint before the indictment is returned would vitiate the time extension.
In this case the Government obtained a superseding indictment before any preliminary hearing took place. Under the interpretation which we have adopted it follows that if the complaint satisfied the requirements of Rules 3 and 4, in particular the probable cause standard of Rule 4, then the nine-month extension had come into *221play and had not been cut off by any later dismissal of the complaint.3 We turn then to the question whether the complaint showed probable cause.
II.
The Jaben complaint read as follows:
“The undersigned complainant, being duly sworn, states:
“That he is a Special Agent of the Internal Revenue Service and, in the performance of the duties imposed on him by law, he has conducted an investigation of the Federal income tax liability of Max Jaben for the calendar year 1956, by examining the said taxpayer’s tax return for the year 1956 and other years; by identifying and interviewing third parties with whom the said taxpayer did business; by consulting public and private records reflecting the said taxpayer’s income; and by interviewing third *222persons having knowledge of the said taxpayer’s financial condition.
“That based on the aforesaid investigation, the complainant has personal knowledge that on or about the 16th day of April, 1957, at Kansas City, Missouri, in the Western District of Missouri, Max Jaben did unlawfully and wilfully attempt to evade and defeat the income taxes due and owing by him to the United States of America for the calendar year 1956, by filing and causing to be filed with the District Director of Internal Revenue for the District of Kansas City, Missouri, at Kansas City, Missouri, a false and fraudulent income tax return, wherein he stated that his taxable income for the calendar year 1956 was $17,665.31, and that the amount of tax due and owing thereon was the sum of $6,017.32, when in fact his taxable income for the said calendar year was the sum of $40,001.76 upon which said taxable income he owed to the United States of America an income tax of $14,562.99.
“[Signed] David A. Thompson
“Special Agent
“Internal Revenue Service
“Kansas City, Missouri.”
Petitioner argues that the complaint is basically indistinguishable from that which the Court found wanting in Giordenello v. United States, 357 U. S. 480. The Giordenello complaint read in relevant part:
“The undersigned complainant being duly sworn states: That on or about January 26, 1956, at Houston, Texas in the Southern District of Texas, Veto Giordenello did receive, conceal, etc., narcotic drugs, to-wit: heroin hydrochloride with knowledge of unlawful importation; in violation of Section 174, Title 21, United States' Code.
*223“And the complainant further states that he believes that-4 are material witnesses in relation to this charge.”
The complaints there and here are materially distinguishable. Information in a complaint alleging the commission of a crime falls into two categories: (1) that information which, if true, would directly indicate commission of the crime charged, and (2) that which relates to the source of the directly incriminating information. The Giordenello complaint gave no source information whatsoever. Its directly incriminating information consisted merely of an allegation in the words of the statute, and even then incomplete, supplemented by “on or about January 26, 1956, at Houston.” If the Jaben complaint were as barren, it would have stated simply that “on or about April 16, 1957, at Kansas City, Missouri, Jaben willfully filed a false income tax return.” In fact, it gave dollars-and-cents figures for the amounts which allegedly should have been returned and the amounts actually returned. As to sources, the affiant indicated that he, in his official capacity, had personally conducted an investigation in the course of which he had examined the taxpayer’s returns for 1956 and other years, interviewed third persons with whom the taxpayer did business and others having knowledge of his financial condition, and consulted public and private records reflecting the taxpayer’s income; and that the conclusion that Jaben had committed the offense was based upon this investigation.
Beyond the substance of the complaint there is a material distinction in the nature of the offense charged. Some offenses are subject to putative establishment by blunt and concise factual allegations, e. g., “A saw narcotics in B’s possession,” whereas “A saw B file a false tax return” does not mean very much in a tax evasion case. *224Establishment of grounds for belief that the offense of tax evasion has been committed often requires a reconstruction of the taxpayer’s income from many individually unrevealing facts which are not susceptible of a concise statement in a complaint. Furthermore, unlike narcotics informants, for example, whose credibility may often be suspect, the sources in this tax evasion case are much less likely to produce false or untrustworthy information. Thus, whereas some supporting information concerning the credibility of informants in narcotics cases or other common garden varieties of crime may be required, such information is not so necessary in the context of the case before us.
Giordenello v. United States, supra, and Aguilar v. Texas, 378 U. S. 108, established that a magistrate is intended to make a neutral judgment that resort to further criminal process is justified. A complaint must provide a foundation for that judgment. It must provide the affiant’s answer to the magistrate’s hypothetical question, “What makes you think that the defendant committed the offense charged?” This does not reflect a requirement that the Commissioner ignore the credibility of the complaining witness. There is a difference between disbelieving the affiant and requiring him to indicate some basis for his allegations. Obviously any reliance upon factual allegations necessarily entails some degree of reliance upon the credibility of the source. See, e. g., Johnson v. United States, 333 U. S. 10, 13. Nor does it indicate that each factual allegation which the affiant puts forth must be independently documented, or that each and every fact which contributed to his conclusions be spelled out in the complaint. Compare United States v. Ventresca, 380 U. S. 102. It simply requires that enough information be presented to the Commissioner to enable him to make the judgment that the charges are not *225capricious and are sufficiently supported to justify bringing into play the further steps of the criminal process.
In this instance the issue of probable cause comes down to the adequacy of the basis given for the allegation that petitioner’s income was $40,001.76 instead of the $17,665.31 he had reported. This is not the type of fact that can be physically observed. The amount of petitioner’s income could only be determined by examining records and interviewing third persons familiar with petitioner’s financial condition. Compare Holland v. United States, 348 U. S. 121. Here the affiant, a Special Agent of the Internal Revenue Service, swore that he had conducted just such an investigation and thereafter swore that he had personal knowledge as to petitioner’s actual income. In such circumstances, the magistrate would be justified in accepting the agent’s judgment of what he “saw” without requiring him to bring the records and persons to court, to list and total the items of unreported income or to otherwise explain how petitioner’s actual income was calculated.
We conclude that the challenged count of this indictment is not time-barred.
Affirmed.
Rule 4 (a) provides:
“If it appears from the complaint that there is probable cause to believe that an offense has been committed and that the defendant has committed it, a warrant for the arrest of the defendant shall issue to any officer authorized by law to execute it. Upon the request of the attorney for the government a summons instead of a warrant shall issue. ... If a defendant fails to appear in response to the summons, a warrant shall issue.”
Rule 5 (c) provides:
“. . . If the defendant waives preliminary examination, the commissioner shall forthwith hold him to answer in the district court. If the defendant does not waive examination, the commissioner shall *218hear the evidence within a reasonable time. The defendant may cross-examine witnesses against him and may introduce evidence in his own behalf. If from the evidence it appears to the commissioner that there is probable cause to believe that an offense has been committed and that the defendant has committed it, the commissioner shall forthwith hold him to answer in the district court; otherwise the commissioner shall discharge him. . . .”
This provision was introduced into the tax laws in 1884 by way of an amendment to a bill providing for a limitation period. In proposing the amendment on the floor of the Senate, Senator Hoar stated:
“As has already been said, this limitation which purports to be a limitation of two years is in point of fact in many districts but a limitation of one year, because the indictment must be found by a grand jury within two years within the commission of the offense. If the offense be concealed, or if it be discovered a year before the grand jury meet, it would be too late to make the prosecution. I move this amendment:
“ ‘Provided, That where a complaint shall be instituted before a commissioner of the United States within the period above limited, the period shall be extended until the discharge of the grand jury at its next session within the district.’
“I think there will be no objection to that.” 15 Cong. Rec. 5771. The time for which the period was extended was changed to nine months in 1954.
A dissenting opinion accepts our interpretation of the statute, but, likening petitioner’s position to one who is incarcerated awaiting a preliminary hearing, argues that petitioner was not scheduled to have a preliminary hearing within the “reasonable time” required by Rule 5 (c). We reject this view of the case. (1) Although the statute should be interpreted to reflect its intent, it greatly overplays that intent to invest the procedure required to effectuate it with the same sense of urgency which might be thought to attend a preliminary hearing for an incarcerated prisoner. (2) A defendant can fully protect himself from unreasonable delay by moving for advancement of the preliminary hearing date and by objecting to any postponements. Petitioner made no such motion or objection, and at no point in the trial or appellate review of this case has he objected to the scheduling of the preliminary hearing.
Mallory v. United, States, 354 U. S. 449, did not deal with preliminary hearings under Rule 5 (c), but with the requirement of Rule 5 (a) that a person who is arrested must be taken “without unnecessary delay before the nearest available commissioner” so that he can be apprised of his rights.
So in original.