
590 N.W.2d 612 (1998)
233 Mich. App. 286
SYNTEX LABORATORIES, Petitioner-Appellant,
v.
DEPARTMENT OF TREASURY, Respondent-Appellee.
Docket No. 196546.
Court of Appeals of Michigan.
Submitted May 5, 1998, at Lansing.
Decided December 29, 1998, at 9:40 a.m.
Released for Publication March 12, 1999.
*614 Miller, Canfield, Paddock, and Stone, P.L.C. (by Samuel J. Mekim, III, P.C., and Joanne B. Faycurry), Detroit, for the petitioner.
Frank J. Kelley, Attorney General, Thomas L. Casey, Solicitor General, and Terry P. Gomoll, Assistant Attorney General, for the respondent.
Before WHITE, P.J., and SAAD and MARKEY, JJ.
SAAD, J.
Petitioner appeals as of right from an opinion and judgment of the Michigan Tax Tribunal affirming deficiency tax assessments against petitioner for the years 1982 and 1983 under the Single Business Tax Act, M.C.L. § 208.1 et seq.; MSA 7.558(1) et seq. We affirm.
Before 1993, respondent utilized PL 86-272, codified at 15 U.S.C. § 381, to determine whether there was a sufficient nexus between a business' activities and the state of Michigan to permit the assessment of the single business tax. Petitioner contended that its activities for the years 1982 and 1983 were insufficient to permit taxation under P.L. 86-272 and sought cancellation of the deficiency assessment. The case was held in abeyance until this Court issued its ruling in Gillette Co. v. Dep't of Treasury, 198 Mich.App. 303, 497 N.W.2d 595 (1993).
In Gillette, id. at 311, 497 N.W.2d 595, this Court held that PL 86-272 did not apply to taxes imposed under the Single Business Tax Act and the proper test is the Due Process/Commerce Clause test (DP/CC test) enunciated in Quill Corp. v. North Dakota, 504 U.S. 298, 112 S.Ct. 1904, 119 L.Ed.2d 91 (1992). That test did not prevent the retroactive imposition of the single business tax *615 against Gillette. Respondent then notified approximately two thousand nonfiling potential taxpayers that they were no longer protected by PL 86-272 and were subject to respondent's jurisdiction pursuant to the Gillette decision. The recipients were asked to voluntarily pay the single business tax for the years 1989[1] to 1993 with interest but without penalty. Respondent did not extend this option to petitioner.
Petitioner then sought relief from the briefing schedule issued by the Tax Tribunal, contending that while it may be subject to taxation under the DP/CC test, application of that test in this case was unconstitutional and that petitioner was entitled to the same treatment as the nonfiling potential taxpayers. The Tax Tribunal denied the motion but limited the issues to be briefed to whether the DP/CC test retroactively applied to petitioner's tax liability for the years 1982 and 1983 and whether respondent could impose liability on petitioner for those years when it had limited the nonfiling potential taxpayers' liability to the years 1989 and after. Petitioner moved to amend its petition to assert those claims and to file a supplemental brief addressing them. The Tax Tribunal denied the former motion but granted the latter. The Tax Tribunal later ruled that respondent's application of the DP/CC test in this case did not violate petitioner's equal protection rights or unlawfully discriminate and affirmed the deficiency assessments.
Petitioner first contends that respondent's application of the DP/CC test for tax years 1982 and 1983 violatedits constitutional rights to equal protection and uniform taxation because it would subject it to treatment different from nonfiling potential taxpayers. We disagree.
Persons are guaranteed equal protection of the laws under the United States and Michigan Constitutions. U.S. Const., Am. XIV; Const. 1963, art. 1, § 2. Michigan's equal protection guarantee is construed no more broadly than the federal guarantee. Gazette v. Pontiac, 212 Mich.App. 162, 173, 536 N.W.2d 854 (1995), remanded 453 Mich. 976, 557 N.W.2d 314 (1996), on remand 221 Mich.App. 579, 561 N.W.2d 879 (1997). The equal protection guarantees require that persons in similar circumstances be treated alike. They do not require that persons in different circumstances be treated the same. Hauser v. Reilly, 212 Mich.App. 184,189, 536 N.W.2d 865 (1995). As a practical matter, there is no discernible difference between the equal protection guarantee and the Uniform Taxation Clause, Const. 1963, art. 9, § 3, which requires uniformity in the general ad valorem taxation of real and personal property and requires all other taxes to be uniform upon the class or classes on which they operate. Ann Arbor v. Nat'l Center for Mfg. Sciences, Inc., 204 Mich.App. 303, 305-306, 514 N.W.2d 224 (1994). Both require that some rational basis for a disputed classification must be shown to exist. Armco Steel Corp. v. Dep't of Treasury, 419 Mich. 582, 592, 358 N.W.2d 839 (1984); In re Pensions of 19th Dist. Judges Under Dearborn Employees Retirement System, 213 Mich.App. 701, 705, 540 N.W.2d 784 (1995). A rational basis shall be found to exist if any set of facts reasonably can be conceived to justify the alleged discrimination. A discriminatory classification that has a rational basis is not invalid simply because it is not mathematically precise in its discrimination or because it results in some inequity. St. Louis v. Michigan Underground Storage Tank Financial Assurance Policy Bd., 215 Mich.App. 69, 73, 544 N.W.2d 705 (1996).
We find that petitioner was not situated similarly to the nonfiling potential taxpayers. Those taxpayers did not have pending matters before respondent, had not been audited, and did not have notice that they would be liable for this state's single business tax for years before 1989 until this Court issued its ruling in Gillette. Petitioner, on the other hand, had a pending matter before respondent, knew that the Gillette decision could affect that matter, and had prior notice that it would be liable for the single business tax for years before 1989. This case is therefore distinguishable from those cases cited by petitioner, principally Armco, supra, Titus v. *616 State Tax Comm., 374 Mich. 476,132 N.W.2d 647 (1965), and MCI Telecommunications Corp. v. Dep't of Treasury, 136 Mich.App. 28, 355 N.W.2d 627 (1984), addressing a claim of unconstitutional administrative discrimination, in which the different groups of taxpayers were similarly situated. We further find that considerations of due process, availability of records, the nonfiling potential taxpayers' reliance on respondent's bulletins, and respondent's limited resources provided a rational basis for respondent's enforcement decision. Therefore, that decision did not violate petitioner's equal protection rights.
Petitioner next asserts that respondent's application of the DP/CC test for tax years 1982 and 1983 violated petitioner's constitutional rights to due process. We disagree.
Persons are guaranteed not to be deprived of life, liberty, or property without due process of law under the United States and Michigan Constitutions. U.S. Const., Am. XIV; Const. 1963, art. 1, § 17. Michigan's due process guarantee is construed no more broadly than the federal guarantee. Gazette, supra. The test to determine whether laws comport with due process is essentially the same as that for equal protection: they must be sustained if rationally related to a legitimate government purpose. Haberkorn v. Chrysler Corp. 210 Mich.App. 354, 381, 533 N.W.2d 373 (1995). As noted, we find that there was a rational basis for respondent's decision regarding enforcement of the DP/CC test announced in Gillette. Therefore, that enforcement decision did not violate petitioner's due process rights.
The general rule is that judicial decisions are to be given complete retroactive effect. Complete prospective application is generally limited to decisions that overrule clear and uncontradicted case law. Hyde v. Univ. of Michigan Bd. of Regents, 426 Mich. 223, 240,393 N.W.2d 847 (1986). Retroactive application of a judicial decision will only violate due process when it acts as an ex post facto law. People v. Doyle, 451 Mich. 93, 100, 545 N.W.2d 627 (1996). However, the ex post facto rule applies only to criminal cases, not to civil cases. Ludka v. Dep't of Treasury, 155 Mich.App. 250, 260, 399 N.W.2d 490 (1986). Nevertheless, retroactive application of a judicial decision can be "problematic" to due process requirements if it is unexpected and indefensible in light of the law existing at the time of the conduct. Doyle, supra at 104, 545 N.W.2d 627. Due process principles prevent retrospective laws from divesting rights to property or vested rights or from impairing contracts. Detroit v. Walker, 445 Mich. 682, 698, 520 N.W.2d 135 (1994). While petitioner may not have expected this Court to reject the P.L. 86-272 test, the Court's decision is not unexpected and indefensible because the appellate courts of this state had never resolved whether the P.L. 86-272 test was appropriate for determining single business tax liability, Gillette, supraat 307, n. 1, 497 N.W.2d 595, and petitioner knew that the Gillette decision could affect its pending matter. In any event, petitioner did not have a vested right in the continuation of any tax law. Walker, supraat 703, 520 N.W.2d 135; Ludka, supra. Therefore, proper application of the law cannot be considered a due process violation in this case.
We also reject petitioner's characterization of respondent's conduct with respect to the nonfiling potential taxpayers as an unlawful granting of administrative amnesty. Respondent did not forgive liability for unpaid taxes for years before 1989, but rather made a decision regarding how to allocate its resources to achieve maximal compliance.
Petitioner next asserts that the Tax Tribunal abused its discretion in denying petitioner's motion to amend its petition. While we agree that the motion should have been granted under the standard enunciated in Ben P. Fyke & Sons v. Gunter Co., 390 Mich. 649, 659, 213 N.W.2d 134 (1973), we find that the error was harmless because the issues petitioner sought to raise in the proposed amendment were legal, not factual, and petitioner briefed and presented the Tax Tribunal these issues.
Petitioner finally argues that even if it is liable for the tax deficiencies and interest, it should not be liable for penalties. This issue has not been preserved for appeal because *617 petitioner did not raise it below and has neglected to brief it. Alford v. Pollution Control Industries of America, 222 Mich. App. 693, 699, 565 N.W.2d 9 (1997); Meagher v. Wayne State Univ., 222 Mich.App. 700, 718, 565 N.W.2d 401 (1997). Therefore we decline to consider it.
Affirmed.
NOTES
[1]  Respondent set 1989 as the cutoff date because of the four-year limitation period on assessment of deficiencies. MCL 205.27a(2); MSA 7.657(27a)(2).
