OPINION OF THE COURT
Milonas, J.In April of 1983, defendant City of New York, through the Department of General Services, solicited bids for contracts to supply fuel oil and kerosene for the period of July 1, 1983 to June 30, 1984. All interested parties were provided with two documents, the standard form of contract, which includes general instructions and conditions, and the requirement contract for fuel oil and kerosene. It is undisputed that these two documents together constitute a binding agreement. According to the standard form of contract, the seller’s bid is considered a firm offer such that "[t]he bidder will accept any awards * * * if they are made within forty-five calendar days” of the opening of bids. However, "[i]f no award is made within forty-five days and the bidder desires to withdraw his bid, he must do so in writing; otherwise his bid remains in effect.” The contract can be modified only in writing and "in a manner not materially affecting the substance hereof, in order to carry out and complete more fully and perfectly the work herein agreed to be done and performed, provided such changes do not result in a net change in cost to the City or to the Seller of the Work to be done under the Contract.” Under the terms of the requirement contract, the bid amount must encompass the cost of the New York State gross receipts tax, which cannot be shown as a separate line item, although the vendor is required to indicate whether or not the bid price contains the gross receipts tax.
Plaintiff Sinram-Marnis Oil Company, Inc., was the low bidder. At the time of its bid, plaintiff was exempt from the gross receipts tax since it was engaged primarily in the sale of fuel for residential purposes. On June 26, 1983, the New York State Legislature adopted a new tax on petroleum businesses, effective June 30, 1983 (Tax Law § 300 et seq., added L 1983, ch 400, § 8). A 314% tax was imposed upon the sale of fuel oil by companies previously exempt from the operation of the *362law, such as plaintiff herein. In the requirement contract which plaintiff had filled out as part of the bidding process, it had, notwithstanding that the tax was not then applicable to the transaction, checked the box marked "yes” with respect to the question of whether the price included the gross receipts tax.
The Deputy Commissioner of the Department of General Services, Carla Lallatin, sent plaintiff a letter of intent, dated June 21, 1983, to enter into a contract. The bid’s 45-day firm offer period expired on June 26, 1983, after which plaintiff was entitled to revoke its bid at any time up to the point that the city accepted the company’s offer. On July 1, 1983, plaintiff’s counsel wrote to Commissioner Lallatin that the gross receipts tax "has not been included in our bid price under this contract. In view of the dramatic impact this 3t4% gross receipts tax will have on our business, we must advise you of our intention to charge this tax to the City of New York, as a separate line item on our invoices, in connection with purchases made pursuant to this contract.”
The city formally accepted plaintiff’s bid pursuant to its notice of award, dated July 6, 1983. The accompanying summary of award contained the price that plaintiff had quoted in its bid, which did not encompass the gross receipts tax. Commissioner Lallatin acknowledged plaintiff’s July 1st communication in a letter dated July 8, 1983 wherein she asserted that "[pjlease be advised that your letter of July 1, 1983, is being forwarded to the Corporation Counsel for a formal opinion regarding the payment of the gross receipts tax. I will keep you informed of the status of this matter and send you a copy of the opinion as soon as I receive it.” Thereafter, the city placed orders for fuel oil with plaintiff in July, August and September of 1983. When plaintiff added the 3lA% gross receipts tax to its invoices, the city refused to remit the amount of the tax. The company then notified the city that it would suspend deliveries unless the deficiency was paid. The néxt day, the Commissioner of the Department of General Services, Robert Litke, informed plaintiff that it was in default of the contract. The city subsequently turned to other suppliers to meet its need for fuel oil and kerosene. It should be noted that the city apparently never followed up on its statement that the opinion of the Corporation Counsel would be solicited and plaintiff advised accordingly.
Plaintiff commenced the instant declaratory judgment action in May of 1984. In its complaint, the company sought a *363declaration that the city was responsible for payment of the gross receipts tax. The city responded by urging that the contract price was the bid price and that the seller was legally precluded from unilaterally raising its price; it also counterclaimed for the. difference between the bid price and the cost of obtaining fuel from substituted vendors after plaintiff refused to continue performance. Defendant City of New York then moved, and plaintiff cross-moved, for summary judgment. In denying defendant’s motion and granting that of plaintiff, the Supreme Court concluded that "[t]he July 1, 1983 letter did constitute a revocation and/or withdrawal of the first offer * * * Although the letter did not contain the words revocation or withdrawal, the letter contained a modification of a material element of the offer which effectively revoked the former offer * * * The letter was sent within the time frame in which a bid could be withdrawn. Despite receiving this communication which evidenced plaintiff’s unwillingness to proceed with the contract under its initial bid, the City proceeded to formalize the contract, therefore acknowledging its acceptance of the new terms. The City, by continuing to do business with Sinram after a material change in the bid of Sinram, accepted Sinram’s proposal.”
The issue of whether a supplier is entitled to pass along the cost of the gross receipts tax where such item was not included in the bid price was recently decided by this court in Burnside Coal & Oil Co. v City of New York (135 AD2d 413). In that case, we declared that (at 414-415):
"The issue at hand is not whether the tax applies to plaintiff or whether an oil company can pass the tax on to a municipal customer, for clearly the answer to both these questions is yes. Rather, the question we must determine is whether under the terms of these contracts plaintiff may pass the tax along to the city. The answer to that is no. The bidding specifications were clear in requiring that any gross receipts tax liability was to be subsumed within the bid itself as a cost of doing business and that the tax could not be billed later on as a separate line item. Thus, the contract was clear in specifying that the tax could not be passed on to the defendant, unless it was included in the bid price of the lowest responsible bidder.
"While plaintiff was exempt from the tax when it submitted its bid and, accordingly, did not incorporate the tax liability in its over-all price bid, it had the opportunity to withdraw its bid after the law became effective. Not only did it not do so, *364but on the day the new tax law became effective, July 1, 1983, it accepted assignment of another fuel contract with the city. There is nothing in the new law which requires the oil company to pass on the tax to the consumer. The tax is directed at the oil company in return for the privilege of doing business in this State. As opposed to the statute, it is the contract terms which will dictate who shall ultimately bear the burden. Not having included the tax when it placed its bid, because it was then inapplicable, and not having exercised its option to withdraw its bid after the tax did become applicable, plaintiff may not unilaterally modify the contract terms at the defendant’s expense. (Manhattan & Queens Fuel Corp. v Village of Rockville Centre, 126 AD2d 523, 524.)”
The Court of Appeals in Manhattan & Queens Fuel Corp. v Village of Rockville Centre (72 NY2d 824), wherein plaintiff fuel company had sought reimbursement from defendant municipality for gross receipt taxes paid to the Tax Commission, recently observed that while a supplier could lawfully pass along this tax burden to a municipal corporation, plaintiff had not done so under its contract with defendant. In addition, the court stated therein, "[pjlaintiff does not claim impracticality or impossibility of performance, but merely claims that the cost of its performance under the contract has increased due to the change in the Tax Law. There is no basis for plaintiff’s claim that defendant is contractually bound to assume this tax burden. Plaintiff, being the party legally obligated to pay the gross receipts tax, must bear the burden of its increased cost in the performance of the contract” (supra at 825).
There is a distinction between the present situation and that in Burnside Coal & Oil Co. v City of New York (supra), as well as the foregoing Court of Appeals case, since plaintiff herein wrote to the city on July 1, 1983, before the latter had formally awarded the contract, to advise that it intended to charge defendant for the gross receipts tax. Thus, the crucial question is whether plaintiff’s letter constituted a revocation of its bid in its original form. In that connection, the Court of Appeals has held that "the purpose of the laws in this State requiring competitive bidding in the letting of public contracts is 'to guard against favoritism, improvidence, extravagance, fraud and corruption.’ * * * These laws were not enacted to help enrich the corporate bidders but, rather, were intended for the benefit of the taxpayers. They should, therefore, be construed and administered 'with sole reference to the public interest’ ” (Matter of Conduit & Found. Corp. v Metropolitan *365Transp. Auth., 66 NY2d 144, 148; see also, Depot Constr. Corp. v City of New York, 46 NY2d 859). Since the public interest is always the paramount concern, common-law contract principles must be applied only in conjunction with a consideration of what is advantageous to the taxpayer.
While it is doubtful that the July 1st letter could be deemed a withdrawal of its bid even under common-law standards, as nothing therein indicates an unwillingness to continue with the contract, the fact remains that plaintiff clearly wanted to supply the city with fuel oil and kerosene but was demanding the right to a separate line item billing for the gross receipts tax. It is evident, however, that the company was precluded from effectuating any modification in the bid following its submission. The standard form of contract specifically provides that once the 45-day firm offer period has expired, a bidder has only two options, to withdraw the bid or leave it in place. Although modifications, which must be in writing, are permitted, these alterations may not "result in a net change in cost to the City or to the Seller”. The modification being sought by plaintiff involved a considerable increase in cost and was, consequently, inconsistent with the terms of the contract. Moreover, the requirement contract mandates that the fuel oil gross receipts tax be part of the bid price; this item may not be billed separately.
Section 103 (2) of the General Municipal Law states that advertisements for public bidding "shall contain a statement of the time when and place where all bids received pursuant to such notice will be publicly opened and read.” Thereafter, that same provision requires that "[a]ll bids received shall be publicly opened and read at the time and place so specified.” Plaintiff, as the low bidder, was awarded the subject contract according to the standards of the competitive bidding law. By now insisting that it be permitted to modify its original bid and bill the city for the gross receipts tax, plaintiff is, in effect, submitting an entirely new bid, thereby claiming a competitive advantage over other potential suppliers. This is simply incompatible with the purposes and legal dictates of the bidding process. In Matter of Tufaro Tr. Co. v Board of Educ. (79 AD2d 376), the court rejected an attempt to invoke the "principle of contract law which holds that an 'offer’ which is not accepted is 'necessarily rejected’ * * * To apply that principle * * * by equating a 'bid’ with an 'offer’ would be to undermine the practice of competitive bidding for public contracts” (at 381). Further, the reasons militating against *366permitting postbid modifications were cogently explained in Matter of Fischbach & Moore v New York City Tr. Auth. (79 AD2d 14, lv denied 53 NY2d 604): "As the name suggests, the practice of competitive bidding seeks value through free and fair competition. Logic and experience teach that competition for public contracts may be promoted only by fostering a sense of confidence in potential bidders that their bids will be fairly considered and that they will not be deprived of any substantial benefit afforded to their competitors * * * To that end, courts have held, for example, that a municipality may not ease contract specifications after bids have been submitted or waive material variances in bids received * * * Were it otherwise, legitimate bidders, who might have been willing to reduce their bids had they known that the specifications of the job would be relaxed, would be unfairly deprived of the opportunity to do so. This, combined with the danger of favoritism, fraud or corruption inherent in a selection process conducted under such circumstances, might well discourage contractors from bidding on future contracts, thus diminishing competition to the detriment of the public * * * Similarly, as the cases relied upon by the petitioner suggest, a municipality may not engage in postbid negotiations through which a contractor other than the low bidder may become the low bidder * * * Were this practice permitted legitimate bidders might be reluctant to participate in the bidding process because of a lack of confidence that their sealed bids would actually determine the contract award” (supra, 79 AD2d, at 20-21).
The court in Matter of Fischbach & Moore v New York City Tr. Auth. (supra) then proceeded to define the circumstances under which postbid modifications could be possible. According to the court, "[t]he crucial question, therefore, is whether the municipal agency, in seeking to conserve public funds, has abided by those rules designed to promote competition and to avoid favoritism and corruption” (supra, at 21). The rules referred to by the court were that there cannot be any suggestion of favoritism, fraud or corruption; the public interest must be advanced through a reduction in the cost of the project; and there may be no departure from the contract’s original specifications and no concessions to the bidder. In the instant matter, acceptance of plaintiff’s new proposal would not only have resulted in a substantial increase in cost to the city, but allowing the amendment would have been unfair to the other bidders. It is certainly not inconceivable that, unlike *367plaintiff, one or more of the next lowest bidders would have been willing to absorb some or all of the gross receipts tax.
Plaintiff contends that common-law principles are often applied in order to interpret or enforce contracts entered into under the public bidding laws, citing City of New York v Long Is. Airports Limousine Serv. (62 NY2d 846), Maross Constr. v Central N. Y. Regional Transp. Auth. (107 AD2d 1010, revd on other grounds 66 NY2d 341), City of Syracuse v Sarkisian Bros. (87 AD2d 984, affd 57 NY2d 618) and Balahan-Gordon Co. v Brighton Sewer Dist. (41 AD2d 246). However, none of the cases relied upon by plaintiff supports the proposition that a bidder may successfully amend the terms of a contract which, as in the present matter, are neither contradictory nor confusing and where no mistake was made in construing the contractual specifications. Indeed, even where a bidder seeks to be relieved from "an error in a value judgment in estimating the requirements or costs necessary to fulfill a contract” (see, Balahan-Gordon Co. v Brighton Sewer Dist., supra, at 249), "[t]he decisive factual question is whether the mistake is one the courts will excuse. Then, if the mistake concerns a material matter in an executory contract under circumstances where relief to the bidder results in no damage to the municipality but enforcement results in serious harm to the bidder, rescission will be granted” (supra, at 250-251). The change desired herein by plaintiff would clearly cause a financial hardship to the city and is, therefore, barred not only by the relevant contractual provisions but by the legal standards pertaining to competitive bidding. Moreover, in the absence of any material facts in dispute, defendant is also entitled to summary judgment in connection with its counterclaim.
Unfortunately, the fervor of the dissent is unsupported by its substance. Thus, on the one hand, the dissent finds that petitioner’s letter of July 1, 1983 effectively revoked the bid, while, on the other, he states that "I think the city ought to be held to the bargain which it may be fairly said to have made in its own interest and that of the public.” However, if the bid has been revoked, how can the city then proceed to award a revoked bid? The illogical and contradictory nature of the dissent’s argument is further indicated by the fact that although he asserts that plaintiff did revoke its original bid, he later treats the revocation as not such at all but, rather, a modification and then proceeds to disregard completely the significance of the standard form of contract, which prohibits modifications except "in a manner not materially affecting the *368substance hereof * * * provided such changes do not result in a net change in cost to the City or to the Seller or to the work to be done under the Contract.” Consequently the so-called revocation is not really a revocation but a modification, and the contract terms may be ignored because "[a]t the time of the bid modification there was no contract to be modified. The cited provision then has no application.” In the final analysis, therefore, the dissent would sanction plaintiffs unilateral modification of its bid and compel the city to accept that modification since "[g]iven the real options available to the city, all of which involved additional costs, the alternative represented by the plaintiffs modified bid was in all probability the least costly one.” Yet, whether or not plaintiffs amended proposal was the least costly is purely speculative. Certainly, to permit a bidder to materially modify its proposal without affording other potential suppliers the opportunity to submit their offers based upon the changed circumstances, which is what the dissent appears to urge, is entirely inconsistent with the purposes and legal dictates of the competitive bidding process.
Order and judgment (one paper) of the Supreme Court, New York County (Karla Moskowitz, J.), entered on March 24, 1987, which, pursuant to a memorandum decision of the court (George Bundy Smith, J.), dated December 24, 1986, denied the motion by defendant City of New York for summary judgment, granted the cross motion by plaintiff Sinram-Marnis Oil Company, Inc. for summary judgment and granted judgment in plaintiffs favor in the amount of $94,455.41, together with interest, costs and disbursements, should be reversed on the law, defendant’s motion for summary judgment dismissing the complaint and on its counterclaim should be granted and plaintiff’s cross motion denied, and the matter remanded for an inquest to determine the amount of recovery on defendant’s counterclaim, without costs or disbursements.