dissenting: I respectfully dissent from the majority opinion regarding the retroactive increase in child support. I agree with the majority that the parties cannot modify a court order by agreement among themselves. I also agree with the majority that pursuant to K.S.A. 60-1610(a), child support automatically terminates when certain events arise.
Bradley Steven, Jr., turned 18 years old on November 6, 1998, and finished high school the following May, which would have extended the obligation for his support until June 30, 1999. Brent *798Steven turned 18 years old on June 18, 2000, at which time the obligation for his support ended.
According to K.S.A. 60-1610(a), child support terminates when the child reaches 18, if the child has completed high school, or until June 30 of the school year during which the child became 18 years of age and graduated from high school. On August 1, 2000, Andrea filed a motion to determine arrearage in child support, stating that the child support for the two older children had terminated; therefore, Bradley owed back support for the two children residing with her.
It is a simple matter to automatically terminate child support when one parent has the custody of the child or children and the other is paying support. That is not the situation in the instant case. What the trial court did was retroactively increase child support.
The decision reached by the majority is in direct conflict with the holding that child support may be modified at any time circumstances render such a change proper, but the modification operates prospectively only. See In re Marriage of Schoby, 269 Kan. 114, 117, 4 P.3d 604 (2000).
The divorce decree in the instant case stated: “Said support shall be paid every month beginning on the 1st day of October, 1997, and continue on the same day each month thereafter until the minor children reach the age of eighteen (18) years of age, unless the minor children are attending high school, in which event child support shall continue until June 30th of that school year.” Such a declaration is in conformity with the law; however, it does not deal with the issue of divided custody, nor how the support should be modified. It certainly does not deal with the issue of retroactive modification, which is what Andrea petitioned for in this case.
In Grunder v. Grunder, 186 Kan. 766, 770, 352 P.2d 1067 (1960), quoting from Davis v. Davis, 145 Kan. 282, 65 P.2d 562 (1937), the court held:
“ ‘A district court has power to modify or change any previous order with respect to payments for the support, maintenance and education of the minor children of a marriage whenever circumstances render such change proper. The new order, however, cannot increase or decrease amounts past due. It must be made effective from the date of modification and not from the date of the original decree or from *799the time of changed circumstances. In other words, the modification must operate prospectively and not retroactively.’ ”
Admittedly, Grunder was not a divided custody case; however, the court has made it clear that there cannot be a retroactive modification. In this instance, where there was a divided custody, the modification should have been made effective from the date of Andrea’s motion for modification. Notwithstanding K.S.A. 60-1610(a), there should not have been a retroactive determination of child support in a divided custody case such as this. I would reverse the trial court’s ruling.