JUSTICE APPLETON delivered the opinion of the court:

The trial court dissolved the marriage of petitioner,Linda S. Waller (n/k/a Sachs), and respondent, Dennis B. Waller,and awarded custody of their son, Joshua Waller, to petitioner. A modified order of support required respondent to pay childsupport until Joshua's eighteenth birthday, September 10, 2001. Joshua was not expected to graduate from high school, however,until May 31, 2002. On behalf of petitioner, the IllinoisDepartment of Public Aid (Department) filed a motion to requirerespondent to continue paying child support until Joshua'sexpected date of graduation. Over respondent's objection, thetrial court granted the motion. Respondent appeals, arguing thatthe trial court should have held an evidentiary hearing toconsider the parties' current financial circumstances. We agree.

We hold that before extending the termination date of asupport order to provide support for an 18-year-old until his orher graduation from high school, the trial court must comply withsections 510(a) and 513 of the Illinois Marriage and Dissolutionof Marriage Act (Dissolution Act) (750 ILCS 5/510(a), 513 (West2000)). By refusing to apply those statutory sections to thefacts of the case, the trial court abused its discretion. Therefore, we reverse the judgment. Because it is clear, fromthe undisputed evidence, that respondent lacked the ability topay child support after Joshua turned 18, an order requiring himto do so could never stand; we remand, however, for entry of anorder fixing the amount of the arrearage.

The modified order of support, entered on March 19,1997, required respondent to pay $320 per month in child support"until September 10, 2001," as well as become current on thethen-existing arrearage. On August 6, 2001, the Department filedits motion to extend child support. The Department alleged thatalthough Joshua would attain the age of majority on September 10,2001, his senior year in high school would not end until May 31,2002. Attached to the motion was a letter, from the high-schoolprincipal, confirming Joshua's expected date of graduation. TheDepartment prayed "[t]hat the [s]upport order continue throughMay[] 2002" and the trial court "enter a judgment" againstrespondent "for arrears."

On October 16, 2001, respondent filed a response to themotion to extend child support, admitting the allegations in themotion but adding that "he [was] unemployed at this time andunable to make extended payments." He prayed that the trialcourt deny the motion for that reason. On the same day, he fileda financial affidavit averring that he was 45 years old, unemployed, and without any source of income. Other than a car,which he valued at $500, he had no assets. His monthly livingexpenses totaled $1,074.

At respondent's request, or with his agreement, thetrial court continued the hearing on the motion several times,until June 4, 2002. In the hearing and in a memorandum he filedbefore the hearing, respondent made a twofold argument: (1)under section 510(d) of the Dissolution Act (750 ILCS 5/510(d)(West 2000)), child support ended when the child turned 18; and(2) a trial court could award postmajority support only undersection 513 of the Dissolution Act (750 ILCS 5/513 (West 2000)),which required a new proceeding in which the trial court considered the parties' current financial circumstances.

After hearing the arguments, the trial court disagreedwith respondent. It explained, in a dialogue with his attorney:

"I respectfully disagree with the propositionthat you can't order [s]ection 505 childsupport after a child turns 18. I think Ihave the authority to modify the order, and Ithink that when the legislature says[,] [insection 505(g),] the termination date shallnot be earlier than age 18[,] *** they couldhave said the termination date shall be nolater than 18. They didn't say that. ***

The problem that I've got here is, beingfair to [respondent], I just don't understandwhy this wasn't heard sooner. If[,] back inSeptember or October of 2001[,] I would havesaid the [m]otion is allowed, then [respondent] knows *** he can file a motion to modify. [He could have said:] [']Hey, Judge, *** I don't like your ruling, but I hear youordered me to pay child support. Now let metell you about this change of circumstancessince that order was entered. I've lost myjob['--]or whatever. That's the problem thatI [have] got.

I think I can continue[,] under [s]ection505[,] a child[-]support [obligation] pastthe [eighteenth] birthday without requiring a[hearing on a possible] change of circumstances *** or without implicating [s]ection513.

*** [I]t is not a [section] 510 modification to extend the termination date [ratherthan change the monthly amount of child support] ***. ***

[Section 505(g) says:] [']Nothing inthis subsection shall be construed to preventthe court from modifying the order.['] ***

[Section] 513 doesn't apply because wehaven't terminated [respondent's] child[-]support obligation under [s]ection 505.

I'm ruling that since [petitioner] fileda motion before the [eighteenth] birthday ofthis child and asked me to modify the termination date[,] *** under [s]ection 505 I havethe authority to do that, and I'm doing it."

Notwithstanding its ruling, the trial court allowedrespondent to make an offer of proof as to his current financialsituation. Respondent testified, essentially, to the facts inhis financial affidavit: his lack of income and assets. Hetestified that after "a long time and a lot of resumes," hefinally landed a job on March 11, 2002, only to be fired sevenweeks later for failing to comply with his employer's unethicaldemands. Respondent insisted he lacked the means to pay childsupport.

In an amended judgment order entered on August 1, 2002,the trial court granted petitioner's motion to extend childsupport until May 31, 2002. The Court held that "it [had] theauthority through [s]ection 505 to do so and that no modificationunder [s]ection 510 [was] implicated[,] nor [was] [s]ection 513implicated." The court found that under the modified order ofsupport, respondent owed $8,611.14 plus statutory interest,whereas under the modified order of support as extended, he owed$11,171.14 plus statutory interest. The court entered a judgmentagainst respondent for the latter figure.

In a motion to reconsider, respondent argued that"[w]hile [s]ection 505(g) does provide the [c]ourt with authorityto modify a support order, this clause is not independent of[s]ection 510." The trial court denied the motion for reconsideration.

This appeal followed.

This appeal turns on the meaning of sections 505, 510,and 513 of the Dissolution Act. We interpret statutes de novo. See Hogan v. Adams, 333 Ill. App. 3d 141, 146, 775 N.E.2d 217,221 (2002). When a party appeals an order modifying an award ofchild support, we ask whether the trial court abused its discretion. In re Marriage of Mulry, 314 Ill. App. 3d 756, 760, 732N.E.2d 667, 671 (2000). The trial court abused its discretiononly if its decision was "clearly against logic." State FarmFire & Casualty Co. v. Leverton, 314 Ill. App. 3d 1080, 1083, 732N.E.2d 1094, 1096 (2000). The question here is whether the trialcourt had the statutory authority to extend respondent's child-support obligation in the fashion it did.

The Department argues that a trial court has the power,in certain circumstances, to order the payment of support beyondthe child's eighteenth birthday. We agree with that truism. Attaining the age of majority, 18 years, is an emancipatingevent. In re Marriage of Ferraro, 211 Ill. App. 3d 797, 799-800,570 N.E.2d 636, 638 (1991). Normally, child support ceases atemancipation, but the parties can agree otherwise or the judgmentcan provide otherwise. 750 ILCS 5/510(d) (West 2000). Section513(a) describes the instances when a trial court "may award sumsof money *** for the support of *** children of the parties whohave attained majority." 750 ILCS 5/513(a) (West 2000). One ofthose instances is when "the child of the parties is stillattending high school, even though he or she attained the age of18." 750 ILCS 5/513(a)(2) (West 2000).

We disagree with the Department that "[i]t is childsupport under section 505, and not educational expenses pursuantto section 513, that is at issue in cases where a child needssupport while finishing high school." Section 513(a)(2) describes "educational expenses" as a type of "support [for] ***children *** who have attained majority," including those in highschool. 750 ILCS 5/513(a)(2) (West 2000). "Support" is simply ageneral term that can include "educational expenses" for a childwho has turned 18 but is still in high school. "Educationalexpenses" may include "room" and "board," just as the moregeneric term, "support," may include shelter and food. A courtcan award "support" to disabled unemancipated children, minor ornonminor (750 ILCS 5/513(a)(1) (West 2000)), and a particularkind of support, "educational expenses," to "nonminor children"in school (750 ILCS 5/513(a)(2) (West 2000)). In short, if thechild has attained majority, the trial court must turn to section513 when deciding whether to award support for that "nonminorchild."

The modified order of support stated that respondent'sobligation to pay support would cease when Joshua ceased being aminor. To require respondent to continue paying support afterJoshua turned 18, the trial court had to change, or "modify," themodified order of support. Therefore, section 510, entitled"Modification *** of provisions for *** support," had obviousrelevance. 750 ILCS 5/510 (West 2000). Section 510(a) providesthat "[a]n order for child support may be modified" in twocircumstances, only one of which (the parties agree) has anypossible applicability to this case: "upon a showing of asubstantial change in circumstances." 750 ILCS 5/510(a)(1) (West2000).

The Department contends that modifying the date theparent may cease paying child support is not truly a modificationwithin the meaning of section 510. It cites two cases holdingthat a parent's obligation to pay child support ends, by operation of law, when the child abandons the parental home (Meyer v.Meyer, 222 Ill. App. 3d 357, 361-62, 583 N.E.2d 716, 719-20(1991)) or gets married (In re Marriage of Daniels, 296 Ill. App.3d 446, 449, 695 N.E.2d 1376, 1378-79 (1998)). The Departmentreasons, by analogy, that the period during which a parent mustpay support extends, by operation of law (without a showing of asubstantial change of circumstances), to the date the 18-year-oldbeneficiary of the support is scheduled to graduate from highschool.

We disagree with the Department's reasoning. Meyer andDaniels relied on section 510(d) of the Dissolution Act (750 ILCS5/510(d) (West 1998)), which provided: "Unless otherwise agreedin writing or expressly provided in a judgment, provisions forthe support of a child are terminated by emancipation of thechild ***." (Emphasis added.) Meyer, 222 Ill. App. 3d at 362,583 N.E.2d at 719-20; Daniels, 296 Ill. App. 3d at 450, 695N.E.2d at 1379. No statute says: "Absent an order or agreement,provisions for the support of a child are extended to the date heor she graduates from high school, regardless of emancipation."

In In re Marriage of Offer, 275 Ill. App. 3d 986, 990,657 N.E.2d 694, 697 (1995), we held that section 510(a) appliedto a petition to extend maintenance. We see no principled reasonto distinguish between an extension of child support and anextension of maintenance; both are a "modification" of an orderof child support or maintenance within the meaning of section510. In In re Marriage of Stanley, 133 Ill. App. 3d 963, 973,479 N.E.2d 1152, 1159 (1985), we held that the "duration" ofmaintenance and child support was "modifiable upon a showing ofsubstantially changed circumstances"--the showing section 510(a)required. We have declined to read into section 510(a) anexception for certain types of modifications. In re Marriage ofTurrell, 335 Ill. App. 3d 297, 310, 781 N.E.2d 430, 442 (2002)(section 510(a) "does not distinguish between 'procedural' and'substantive' changes").

To require continued support until graduation day, thetrial court had to change the modified order of support byeffectively drawing a line through the words "until September 10,2001," and substituting the words "until May 31, 2002." Amodification is a modification. Section 510(a) imposes conditions for modifying an order of support and, on its face, makesno exception for extending the period during which the parentmust pay support. We will not interpret an unambiguous statuteas having subtle exceptions or limitations that are absent fromthe text. Lauer v. American Family Life Insurance Co., 199 Ill.2d 384, 390-91, 769 N.E.2d 924, 928 (2002). If the legislatureintended to make an exception for modifying the duration ofsupport, it surely would have considered the exception importantenough to say so in section 510. Increasing the period duringwhich the parent must pay monthly support means more money out ofthe parent's pocket, just as surely as increasing the monthlyamount.

In section 505(g), the trial court purported to findauthority, separate and distinct from section 510, to change themodified order of support. Specifically, the trial court reliedon the language in section 505(g) that "[t]he termination dateshall be no earlier than the date on which the child covered bythe order will attain the age of majority or is otherwise emancipated" and "[n]othing in this subsection shall be construed toprevent the court from modifying the order." (Emphasis added.) 750 ILCS 5/505(g) (West 2000). Just because a court can orderpostmajority support, it does not follow that it has unfettereddiscretion to do so. Further, just because nothing in section505(g) prevents a court from modifying a support order, it doesnot follow that nothing in section 510(a)--or, for that matter,any other section of the Dissolution Act, such as section 513--prevents the modification.

The Department argues that even if section 510 wasapplicable, the evidence showed a substantial change of circumstances in that Joshua would not graduate from high school untilMay 2002. We do not understand how Joshua's expected date ofgraduation was a change in circumstances. The Department offersno explanation and does not cite any pages of the record thatshed light on that question. A "change in circumstances," withinthe meaning of section 510(a)(1), is a change that occurredsometime after the entry of the modified order of support. SeeIn re Marriage of Hughes, 322 Ill. App. 3d 815, 819, 751 N.E.2d23, 26 (2001). According to the petition for a judgment ofdissolution, Joshua was born on September 10, 1983. Presumably,he would not have started kindergarten until 1989. By our count,he was right on schedule when he began his senior year of highschool in 2001, the year he turned 18. The parties must haveknown, from the date of Joshua's birth, that he would reach theage of majority before graduating from high school.

"When determining whether there is sufficient cause tomodify, courts consider both the circumstances of the parents andthe circumstances of the child." In re Marriage of Lambdin, 245Ill. App. 3d 797, 806, 613 N.E.2d 1381, 1389 (1993). The trialcourt erroneously concluded that respondent's financial circumstances were irrelevant. "For a modification to occur, theremust be a change in the child's needs, an increase in the father's income, or a change in the financial condition of themother." In re Marriage of Pettifer, 304 Ill. App. 3d 326, 328,709 N.E.2d 994, 996 (1999). The record contains no evidence ofany of those changed circumstances.

Even if the evidence did show a substantial change incircumstances, we would nevertheless reverse the trial court'sjudgment because the trial court refused to consider the factorsin section 513(b) and thereby caused substantial prejudice torespondent. Section 513(b) provides:

"In making awards under paragraph ***(2) of subsection (a) [(which allows supportfor 18-year-olds who are still in highschool)], *** the court shall consider allrelevant factors that appear reasonable andnecessary, including:

(1) The financial resources of bothparents.

(2) The standard of living thechild would have enjoyed had the marriage not been dissolved.

(3) The financial resources of thechild.

(4) The child's academic performance." 750 ILCS 5/513(b) (West 2000).

Like section 510 of the Dissolution Act, section 513was directly applicable to this case, and the trial court erredin sidestepping both of those sections. Section 510 was applicable because the trial court was modifying a support order. Section 513 was applicable because the trial court was"award[ing] sums of money *** for the support of [a] child ***who [had] attained majority." 750 ILCS 5/513(a) (West 2000).

We disagree with respondent that the trial court'sfailure to follow sections 510 and 513 deprived it of jurisdiction. Subject-matter jurisdiction flowed from the IllinoisConstitution, not from the Dissolution Act. See BellevilleToyota, Inc. v. Toyota Motor Sales, U.S.A., Inc., 199 Ill. 2d325, 335, 770 N.E.2d 177, 185 (2002). Nevertheless, the trialcourt disregarded controlling statutory law, to the substantialprejudice of respondent, and thereby abused its discretion. SeeLeverton, 314 Ill. App. 3d at 1083, 732 N.E.2d at 1096. A courtshould not order a parent to pay a greater amount of support thanthe parent can reasonably afford. In re Support of Pearson, 111Ill. 2d 545, 552, 490 N.E.2d 1274, 1277 (1986).

For the foregoing reasons, we reverse the trial court'samended judgment order. Respondent remains obligated, however,to pay the arrears in child support that accrued prior to September 10, 2001; we remand for entry of a judgment order stating thearrearage ($18,611.14) and statutory interest calculated consistent with Burwell v. Burwell, 324 Ill. App. 3d 206, 753 N.E.2d1259 (2001).

Reversed; cause remanded with directions.

KNECHT and McCULLOUGH, JJ., concur.