delivered the opinion of the court:
This case involves the evidentiary effect given to a Department of Revenue estimated tax correction predicated upon a computer printout.
Plaintiff, Grand Liquor Company, Inc., received a final assessment for an alleged tax deficiency due under the Retailers’ Occupation Tax Act (Ill. Rev. Stat. 1973, ch. 120, par. 440 et seq.), and the Municipal Retailers’ Occupation Tax Act (Ill. Rev. Stat. 1973, ch. 24, par. 8—11—1) from the Department of Revenue of the State of Illinois (hereinafter referred to as the Department).
There were four administrative hearings held at which the Department’s auditor who corrected the returns was present to answer questions. On examination by the hearing officer the auditor stated that he based his correction on a computer printout which relates to the records on file with the State in Springfield as to payment of the retailers’ occupation tax and municipal retailers’ occupation tax. On cross-examination by the taxpayer’s attorney, the auditor testified that the correction was based on “sales tax returns, monthly filing of these returns, [and] the receipts.” He also asserted that an additional 20% fraud penalty was added to the estimated assessment based on the computer results. Pursuant to further questioning, the auditor for the Department acknowledged that he did not know what data were fed into the computer and that the end-result answer was controlled by the computer and measured by the conditions of and basic input to the electronic machine.
The circuit court of Cook County confirmed the Department’s assessment. However, the appellate court in Grand Liquor Co. v. Department of Revenue (1976), 36 Ill. App. 3d 277, reversed the circuit court and remanded the cause for a new hearing by the Department, holding that before the Department’s correction of the retailers’ occupation tax returns based on the computer printout is deemed prima facie proof of its correctness pursuant to the Retailers’ Occupation Tax Act (Ill. Rev. Stat. 1973, ch. 120, par. 443), the Department must explain the method it employed in reaching the assessment.
Section 4 of the Retailers’ Occupation Tax Act (Ill. Rev. Stat. 1973, ch. 120, par. 443) provides for the examination and the correction of returns:
“As soon as practicable after any return is filed, the Department shall examine such return and shall, if necessary, correct such return according to its best judgment and information, which return so corrected by the Department shall be prima facie correct and shall be prima facie evidence of the correctness of the amount of tax due, as shown therein. In correcting transaction by transaction reporting returns provided for in Section 3 of this Act, it shall be permissible for the Department to show a single corrected return figure for any given period of a calendar month instead of having to correct each transaction by transaction return form individually and having to show a corrected return figure for each of such transaction by transaction return forms. In making a correction of transaction by transaction, monthly or quarterly returns covering a period of 6 months or more, it shall be permissible for the Department to show a single corrected return figure for any given 6-month period.
Instead of requiring the person filing such return to file an amended return, the Department may simply notify him of the correction or corrections it has made.
Proof of such correction by the Department may be made at any hearing before the Department or in any legal proceeding by a reproduced copy of the Department’s record relating thereto in the name of the Department under the certificate of the Director of Revenue. Such reproduced copy shall without further proof, be admitted into evidence before the Department or in any legal proceeding and shall be prima facie proof of the correctness of the amount of tax due, as shown therein.” (Emphasis added.) Ill. Rev. Stat. 1973, ch. 120, par. 443.
Under this Act “\p]roof of such correction by the Department may be made at any hearing before the Department or in any legal proceeding by a reproduced copy of the Department’s record relating thereto ***. Such reproduced copy [of the Department’s record] shall without further proof, be admitted into evidence before the Department or in any legal proceeding and shall be prima facie proof of the correctness of the amount of tax due, as shown therein. ” (Emphasis added.) (Ill. Rev. Stat. 1973, ch. 120, par. 443.) Previous to the advent of computer use by the Department in the assessment of tax deficiencies, the corrected returns, deemed to be prima facie correct, were products of the Department auditors’ personal investigations, computations, and verifications of records, invoices, or other data. At a hearing to challenge the additional tax imposed by the correction, an auditor who corrected the returns, or another personally familiar with the case involved, would be present to answer questions as to the nature of the personal computations of the corrected assessment. Anderson v. Department of Finance (1938), 370 Ill. 225; Copilevitz v. Department of Revenue (1968), 41 Ill. 2d 154; Du Page Liquor Store, Inc. v. McKibbin (1943), 383 Ill. 276; Novicki v. Department of Finance (1940), 373 Ill. 342.
The general question raised for the first time before this court is whether, within the meaning of the Retailers’ Occupation Tax Act (Ill. Rev. Stat. 1973, ch. 120, par. 443), an estimated tax correction based upon a computer printout should, “without further proof,” be accorded prima facie evidentiary status as to “the correctness of the amount of tax due.”
Under the conventional nonautomated record-keeping method of correction, the taxpayer, confronted with the deficiency under the Retailers’ Occupation Tax Act, was afforded the opportunity to cross-examine a department auditor personally knowledgeable of the source records and accounting method of assessment. The problem we now face is that evidentiary rules must accommodate the automated record-keeping systems of sophisticated technology.
A computer printout is a figure result of electronic data processing: data from written documents is keypunched on cards, then transferred onto magnetic tapes or magnetic disks and processed according to a program consisting of a list of instructions in machine language fed to the computer on cards, tapes or disks.
Three potential sources of error underlie a computer record-keeping, data-processing system: “the input of information by encoding or translating it [source documents] into machine language, the creation of the program which instructs the computer, and the actual mechanical operation of the machine.” (Tapper, Evidence from Computers, 8 Ga. L. Rev. 562, 566 (1974).) Moreover, “if the information from which the print-out is made has not been accurately compiled the computer’s output will be similarly incorrect.” (8 Ga. L. Rev. 562, 567.) The latter aspect has been succinctly described in the cybernetics maxim, “garbage in, garbage out.” 8 Ga. L. Rev. 562, 567.
Although section 8 of the Retailers’ Occupation Tax Act dictates that the conduct of an investigation or hearing shall not be bound by the technical rules of evidence (Ill. Rev. Stat. 1973, ch. 120, par. 447), this court has previously recognized in Novicki v. Department of Finance (1940), 373 Ill. 342, that the legislature did not intend this provision to abrogate the fundamental rules of evidence. We asserted further that the rule against hearsay evidence “is founded on the necessity of an opportunity for cross-examination, and is a basic and not a technical rule.” 373 Ill. 342, 344.
The record shows that on March 9, 1972, the date of the first hearing held by the Department of Revenue, in relation to the introduction of the “correction of returns,” the following dialogue took place on direct examination between the hearing referee of the Department, and Mr. Carey Blum, an auditor with the Department of Revenue, the only State witness:
“Q. What did you next then do?
A. Because the books and records have not been made available nor has the taxpayer returned my calls, an estimated assessment was set up and a 20 percent civil fraud penalty was added to the liability authorized by Mr. Frank Frioti (phonetic).
Q. What was the basis of your estimated liability?
A. The basis of the estimated liability was on the information given me by the still on a computer print out which states the records on file with the state in Springfield as far as payment of Retailers’ Occupation Tax and Municipal Tax.
Q. And what was the estimate you based on those records?
A. The estimate was based on my estimate; that is, records showed one half his assets understated.
Q. And using one half of the assets as reported, you set up a correction return, is that correct?
A. Yes, I did.
Q. Which was the basis for the Notice of Tax Liability?
A. Yes.
MR. JACOBSON: Do you wish to cross-examine?
MR. PHILLIPS: Yes. I now express an objection to their schedule of corrected returns submitted by this witness apparently on the basis that number one, it is not based on the Taxpayer’s books and records. Number two, it is not based, I don’t believe, upon a showing of the next best evidence other than books and records; and certainly on the basis that it is an opinion and a conjecture of someone from Springfield other than this witness.
THE WITNESS: No, it is a computer print out of the information.
Examination By Mr. Phillips
Q. But you didn’t feed the information into the computer?
A. No, I didn’t.
Q. You do not know what information went in?
A. I know what was given to me.
Q. I say again, you do not know what information went in?
A. Yes.
Q. You do know enough about computer statistical reporting to agree with me, I believe, that the end result and the answer that comes back from the computer is controlled and measured by what are the conditions, what are the basics that are fed in?
A. Yes.
Q. And you do not know of your own knowledge what was fed in?
A. Correct.”
The record continues:
“MR. PHILLIPS: Let me put it this way, if for some unforeseen reason I cannot get those books and records and then I am stuck with seeing how accurate is this; and I am saying if for some unforeseen reason I am denied and you are denied the right to proceed intelligently with the books and records, then I must determine how reasonable is this, is this conjecture.
MR. JACOBSON: But, I am going to give you the opportunity to bring in the books and records; and I will give you a continued date for the propose of obtaining the books and records and bring your books and records which would be the sales journal, general ledger, federal income tax reports, substantiation of any claimed non taxable receipts.
I will give you that opportunity because we have been denied that opportunity up to this date; and as the statute provides, we made out our prima facie case. The burden will now shift to you to offer affirmative evidence, which I am giving you.”
It seems clear to us that the State attempted to use the statute to make a prima facie case in an attempt to induce the appellant to surrender his books and records in order to arrive at an accurate assessment of the tax he owed. We feel that this was the intention of the legislature in enacting the statute, but that it was not the intent of the legislature to allow any document styled by the Department as a “corrected assessment” to be “prima facie” evidence against the taxpayer, especially, as in this case, where the Department’s sole evidence lacked any background information on the accuracy of the computer printout. As a result, meaningful examination could not be conducted to determine if the corrected return was in fact based upon the Department’s best judgment and information.
The Supreme Court of Mississippi recognized the admissibility of computer evidence when it stated:
“In sum, we hold that print-out sheets of business records stored on electronic computing equipment are admissible in evidence if relevant and material, without the necessity of identifying, locating and producing as witnesses the individuals who made the entries in the regular course of business if it is shown (1) that the electronic computing equipment is recognized as standard equipment, (2) the entries are made in the regular course of business at or reasonably near the time of the happening of the event recorded, and (3) the foundation testimony satisfies the court that the sources of information, method and time of preparation were such as to indicate its trustworthiness and justify its admission.” King v. State ex rel. Murdock Acceptance Corp. (Miss. 1969), 222 So. 2d 393, 398.
We agree that computer records may be admissible under Supreme Court Rule 236 (58 Ill. 2d R. 236), but we hold that the Department did not sufficiently lay the proper foundation for the introduction of such records upon which the “corrected assessment” was founded, the result being that the Department failed to establish the prima facie evidence of the correctness of the amount of tax due. For the reasons stated, the judgment of the appellate court is affirmed and the cause remanded to the Department of Revenue for a new hearing consistent with the directions expressed here.
Affirmed and remanded, with directions.