227 F.3d 1009 (7th Cir. 2000)
Mark F. Elmore, Plaintiff-Appellant,v.William J. Henderson, Postmaster General, Defendant-Appellee.
No. 99-3783
In the  United States Court of Appeals  For the Seventh Circuit
Argued August 9, 2000Decided September 14, 2000

Appeal from the United States District Court  for the Southern District of Indiana, Indianapolis Division.  No. IP-98-1664-C-B/S--Sarah Evans Barker, Chief Judge.
Before Posner, Ripple, and Williams, Circuit Judges.
Posner, Circuit Judge.


1
This appeal from the  dismissal of the plaintiff's suit because the  statute of limitations had run presents a tangle  of important statute-of-limitations issues. The  plaintiff filed a suit along with two other  persons against the Postal Service charging  violations of Title VII and the Rehabilitation  Act. The suit was filed on February 23, 1998,  which, so far as Elmore was concerned, was the  84th day of the 90-day period within which the  suit had to be filed after the final decision by  the Postal Service turning down his  administrative complaint. 29 C.F.R. sec.  1614.407. The judge dismissed Elmore and one of  the other two plaintiffs, without prejudice, on  the ground of misjoinder because the three  plaintiffs' claims did not arise out of the same  event or series of events. Fed. R. Civ. P. 20(a),  21; Intercon Research Associates, Ltd. v. Dresser  Industries, Inc., 696 F.2d 53, 57 (7th Cir.  1982); Alexander v. Fulton County, 207 F.3d 1303,  1323-24 (11th Cir. 2000); Abdullah v. Acands,  Inc., 30 F.3d 264, 268 n. 5 (1st Cir. 1994). That  was on August 5, 1998. After the remaining  plaintiff settled with the defendant, the judge  dismissed the entire suit with prejudice. That  was on October 22, 1999; earlier, on December 4,  1998, Elmore had refiled his claim as a separate  suit. The district judge dismissed the refiled  suit with prejudice because it had not been filed  within the six days remaining of the original  limitations period when Elmore was dismissed from  the suit or even within 90 days following that  dismissal. Elmore argues that because the  original suit was timely, his second suit should  have been treated simply as a continuation of the  original suit, especially since, he further  argues, the judge erred in dismissing him from  the original suit. Alternatively, he argues that  the running of the statute of limitations on the  second suit should be equitably tolled.


2
The filing of a suit stops the running of the  statute of limitations, though only contingently.  It is true that if the suit is later dismissed  with prejudice, any issue concerning the bar of  the statute of limitations to the refiling of the  suit will be moot because a suit that has been  dismissed with prejudice cannot be refiled; the  refiling is blocked by the doctrine of res  judicata. But if the suit is dismissed without  prejudice, meaning that it can be refiled, then  the tolling effect of the filing of the suit is  wiped out and the statute of limitations is  deemed to have continued running from whenever  the cause of action accrued, without interruption  by that filing. E.g., Conover v. Lien, 87 F.3d  905, 908-09 (7th Cir. 1996); Beck v. Caterpillar  Inc., 50 F.3d 405, 407 (7th Cir. 1995); Powell v.  Starwalt, 866 F.2d 964, 966 (7th Cir. 1989);  Chico-Velez v. Roche Products, Inc., 139 F.3d 56,  59 (1st Cir. 1998); Johnson v. Nyack Hospital, 86  F.3d 8, 11 (2d Cir. 1996); Garfield v. J.C.  Nichols Real Estate, 57 F.3d 662, 666 (8th Cir.  1995).


3
In other words, a suit dismissed without  prejudice is treated for statute of limitations  purposes as if it had never been filed. E.g.,  Beck v. Caterpillar Inc., supra, 50 F.3d at 407;  Lambert v. United States, 44 F.3d 296, 298 (5th  Cir. 1995); Dade County v. Rohr Industries, Inc.,  826 F.2d 983, 989 (11th Cir. 1987). Were this not  the rule, statutes of limitations would be easily  nullified. The plaintiff could file a suit,  dismiss it voluntarily the next day, and have  forever to refile it. The strongest case for the  rule that the running of the statute of  limitations is unaffected by a dismissal without  prejudice is therefore the case in which the  plaintiff procured the dismissal, as by  voluntarily dismissing the suit. See, e.g.,  Willard v. Wood, 164 U.S. 502, 523 (1896); Beck  v. Caterpillar Inc., supra, 50 F.3d at 407;  Bonneville Associates, Limited Partnership v.  Barram, 165 F.3d 1360, 1364 (Fed. Cir. 1999). But  that cannot place limits on the scope of the  rule, since a plaintiff can almost always  precipitate a dismissal without prejudice, for  example by failing to serve the defendant  properly or by failing to allege federal  jurisdiction, even if he does not move to dismiss  it. The rule is therefore as we stated it: when a  suit is dismissed without prejudice, the statute  of limitations is deemed unaffected by the filing  of the suit, so that if the statute of  limitations has run the dismissal is effectively  with prejudice. E.g., Duffy v. Ford Motor Co.,  218 F.3d 623, 629 (6th Cir. 2000); Hatchett v.  Nettles, 201 F.3d 651, 652-53 (5th Cir. 2000)  (per curiam). The severity of the rule is  mitigated, however, by the doctrine of equitable  tolling, as we'll see.


4
When there are several plaintiffs in a single  suit and one is dismissed out, whether under Rule  21 or any other rule or doctrine, it is as if he  had brought a separate suit that was dismissed.  We cannot find a case on the point; but it seems  to us clear as a matter of first principles. The  purpose of Rule 20(a) in permitting joinder in a  single suit of persons who have separate claims,  albeit growing out of a single incident,  transaction, or series of events, is to enable  economies in litigation, not to merge the  plaintiffs' rights so that the defendant loses  defenses that he might have had against one of  the plaintiffs. It is true that the statute of  limitations is tolled for class members until it  is determined that the case cannot proceed as a  class action, Crown, Cork & Seal Co. v. Parker,  462 U.S. 345, 352-53 (1983); American Pipe &  Construction Co. v. Utah, 414 U.S. 538, 551-52  (1974); Hemenway v. Peabody Coal Co., 159 F.3d  255, 265-66 (7th Cir. 1998), but that is because  a class action is not a mere "invitation to  joinder." American Pipe & Construction Co. v.  Utah, supra, 414 U.S. at 550. It is a device  centrally concerned with the economies of  aggregating small claims, and it would thus be  seriously impaired by a rule that required all  the class members to file separate, protective  suits, against the eventuality that the statute  of limitations would run during the period when  the class status of the putative class action  remained undetermined. We want the class members  to rely on the filing of the class action rather  than to clutter the courts with a multitude of  separate suits.


5
There is in any event little risk that a  determination that claims have been misjoined  will lead to a dismissal with statute of  limitations consequences, since, as we're about  to see, the district court is duty-bound to  prevent those consequences by severing rather  than dismissing claims. If it fails in that duty,  the remedy is appeal.


6
Hence the dismissal of Elmore from the suit on  August 5, 1998, occurred long after the 90-day  period within which he had to sue had elapsed,  and was time barred before that date, not six,  let alone 96, days later. Cf. Wilson v. Grumman  Ohio Corp., 815 F.2d 26, 27-28 (6th Cir. 1987)  (per curiam). The judge erred in thinking that  the statute of limitations was tolled between the  filing of the original suit and when she  dismissed Elmore from it.


7
It is irrelevant that the dismissal was almost  certainly erroneous, not because there wasn't  misjoinder, but because in formulating a remedy  for a misjoinder the judge is required to avoid  gratuitous harm to the parties, including the  misjoined party. Rule 21 not only requires that  orders adding or dropping parties be made "on  such terms as are just," but also expressly  allows the judge to sever the misjoined party's  claim rather than dismiss it. Sabolsky v.  Budzanoski, 457 F.2d 1245, 1249 (3d Cir. 1972).  The judge could and should have allowed Elmore's  claim against the Postal Service to continue as a  separate suit so that it would not be time-  barred. Rice v. Sunrise Express, 209 F.3d 1008,  1014 n. 8 (7th Cir. 2000); White v. ABCO  Engineering Corp., 199 F.3d 140, 145 n. 6 (3d  Cir. 1999). As an offshoot of the original suit,  Elmore's separate, severed suit, though separate  from the original suit for other purposes, would  not have affected the tolling of the statute of  limitations by the original suit. That is, it  would have been a continuation of the original  suit so far as he was concerned. This would be  obvious if the judge had dismissed the other two  plaintiffs from the suit, leaving Elmore as the  sole plaintiff, rather than dismissing Elmore and  one of the two other plaintiffs; and we do not  think the running of the statute of limitations  should be affected by which joined plaintiffs are  dismissed.


8
But waiving the statute of limitations is not  the proper remedy for an erroneous dismissal. The  proper remedy is appeal. Although the suit  continued in the district court on behalf of the  remaining plaintiff, and so the dismissal of  Elmore was not a final judgment in the usual  sense, Rule 54(b) allows the district judge to  enter a final, immediately appealable judgment  from an order that dismisses one of the parties.  See House v. Belford, 956 F.2d 711, 716 (7th Cir.  1992); In re Southeast Banking Corp., 69 F.3d  1539, 1547 (11th Cir. 1995); Haynesworth v.  Miller, 820 F.2d 1245, 1252-53 (D.C. Cir. 1987).  Elmore did not ask for such a judgment.


9
So the statute of limitations ran long before  Elmore refiled his suit. That in itself need not  have been fatal. There are defenses to the  statute of limitations, and Elmore is right in  identifying equitable tolling as one of them. The  running of a statute of limitations can be  equitably tolled when through no fault of his own  the plaintiff was unable to sue within the  limitations period but he sued as soon as he  could. E.g., Flight Attendants Against UAL Offset  v. Commissioner, 165 F.3d 572, 575-76 (7th Cir.  1999); Donald v. Cook County Sheriff's Dept., 95  F.3d 548, 561-62 (7th Cir. 1996); Cada v. Baxter  Healthcare Corp., 920 F.2d 446, 451 (7th Cir.  1990); Graham-Humphreys v. Memphis Brooks Museum  of Art, Inc., 209 F.3d 552, 560-61 (6th Cir.  2000). This, however, is not a case in which the  plaintiff was prevented from suing within the  limitations period. He did sue within that  period. His complaint is that his suit was  erroneously dismissed, as a result of which,  though the dismissal was without prejudice, his  claim was lost because the statute of limitations  ran before he refiled. Equitable tolling is not a  remedy for an erroneous judgment; appeal, or in  exceptional cases a motion under Fed. R. Civ. P.  60, is.


10
For completeness we note that, even if equitable  tolling could do service here for an appeal, as  assumed (rather than discussed) in Justice v.  United States, 6 F.3d 1474, 1480-82 (11th Cir.  1993), the doctrine would be unavailable to  Elmore in the circumstances of this case. It is  true that he cannot be faulted for having failed  to refile his suit before the district court  dismissed him from the original one. He had no  reason to anticipate an erroneous order  dismissing him for misjoinder rather than just  severing his claim and allowing it to continue as  a separate suit. But he could not possibly invoke  the doctrine of equitable tolling unless he sued  just as soon as possible after the judge's action  made him realize that the statute of limitations  had run. He waited four months to sue and has  offered no excuse for the delay. Since all he had  to do was refile the original complaint, merely  deleting reference to his coplaintiff's claims,  it is not surprising that he is unable to come up  with an excuse.


11
We have emphasized in previous cases the social  importance of limitations periods for suing.  E.g., Cook v. City of Chicago, 192 F.3d 693, 696  (7th Cir. 1999); Galloway v. General Motors  Service Parts Operations, 78 F.3d 1164, 1165-66  (7th Cir. 1996); see also Delaware State College  v. Ricks, 449 U.S. 250, 259-60 (1980); Dring v.  McDonnell Douglas Corp., 58 F.3d 1323, 1330 (8th  Cir. 1995). Such deadlines minimize legal  uncertainty both about the outcome of eventual  litigation and about the existence and scope of  the potential defendant's liability. Burnett v.  New York Central R.R., 380 U.S. 424, 428 (1965);  Bailey v. International Brotherhood of  Boilermakers, Etc., Local 374, 175 F.3d 526, 531  (7th Cir. 1999); Servicios-Expoarma, C.A. v.  Industrial Maritime Carriers, Inc., 135 F.3d 984,  989 (5th Cir. 1998); Sperling v. Hoffmann-La  Roche, Inc., 24 F.3d 463, 471-72 (3d Cir. 1994).  The importance of the limitations period in the  present case is underscored by the brevity of  that period. By fixing 90 days as the deadline  for suing after final agency action, the Postal  Service has emphasized the urgency of prompt  resolution of employment claims against it. The  practical reason for that sense of urgency in an  employment case is that an employer's liability  tends to mount up with each day that judgment is  deferred, since back pay (in a dismissal case)  accumulates from the dismissal of the plaintiff  to his reinstatement following the entry of a  judgment for him. Cook v. City of Chicago, supra,  192 F.3d at 696; Cada v. Baxter Healthcare Corp.,  supra, 920 F.2d at 452-53.


12
Affirmed.

