M.J. KELLY, J.

Plaintiff appeals as of right from an order of the circuit court denying his petitions to reduce child support payments and to eliminate child support arrearages. The trial court also denied plaintiff's request for custody of the minor child but plaintiff does not appeal from that portion of the order. We affirm in part and reverse in part.

Plaintiff and defendant are the parents of Lucas James Joslin, born October 23, 1982. Although the parties have never married, paternity is not here disputed. The parties were living together at the time of their son's birth and on May 4, 1983, plaintiff acknowledged paternity and stipulated to child support payments of $21 per week, resolving a paternity action filed by defendant following their separation. An order of child support was entered on May 13, 1983.

On December 20, 1984, plaintiff filed a complaint for custody of Lucas. He subsequently filed petitions to reduce child support and eliminate arrearages. Following a hearing conducted on March 8, 1985, the trial court awarded custody to the defendant and denied plaintiff's petitions, except that plaintiff was relieved of child support arrearages accumulated during any time Lucas was in the care of plaintiff for a period of seven days or more.

Plaintiff first argues on appeal that the trial court abused its discretion in denying his petition to reduce his child support obligation as set forth in the order of May 13, 1983. We do not agree. At the time plaintiff's petition was denied, he was self-employed as a woodcutter and earning $50 per week. Plaintiff is mentally and physically healthy and offered no reason as to why he is unable to obtain full-time or additional part-time employment. A trial court is not limited to a parent's actual income in setting child support payments and may consider unexercised ability to earn. Wilkins v Wilkins, 149 Mich. App. 779, 792; 386 N.W.2d 677 (1986). We agree with the trial court's observation that $21 per week is a minimal sum and is within plaintiff's ability to pay.

Moreover, since this is a petition for modification of a child support obligation, plaintiff must allege and prove a change in circumstances sufficient to justify the request. Wells v Wells, 144 Mich. App. 722, 733-734; 375 N.W.2d 800 (1985). Plaintiff in this case has failed to do either. At the time the original support order of $21 per week was entered, plaintiff had a bi-weekly income of only $140, which he also used to support two minor children from a previous marriage in his custody. Plaintiff's income at the time of his modification petition was $50 per week but he no longer had any support obligation for the care of the two other minor children. Given our de novo review of this case, we are persuaded that the trial court did not abuse its discretion in refusing to reduce plaintiff's child support obligation below $21 per week.

Plaintiff also argues that the trial court erred in refusing to eliminate arrearages accumulated during the time that plaintiff's sole source of income was welfare. At the time Lucas was born, plaintiff had primary physical custody of his two other children and was receiving public assistance benefits of $140 every other week. He continued to receive these benefits until February 5, 1985, when the two children began living with their mother. At about the same time, plaintiff commenced his wood-cutting employment.

We are persuaded that plaintiff's child support arrearages should be reduced by the amount which accumulated during the period in which plaintiff had physical custody of his two other children and was dependent upon ADC benefits as his sole source of support. In determining support obligations, a trial court must consider both parents' abilities to pay as well as the needs of the minor child. We fail to see how plaintiff was able to financially support Lucas when he was responsible for the daily maintenance, care and support of his two other minor children. This is not a situation in which plaintiff father was unemployed and had considerable free time within which to earn $21 a week to contribute to the care of a minor child. Rather, plaintiff's time was occupied with the care of two minor children who presumably would have required alternative child care at some cost to plaintiff had he acquired employment so as to pay $21 per week support.

To the extent that Lucas was not being provided adequate support or care, he was entitled to the same ADC benefits which provided for the support and care of plaintiff's other two children. We find it inappropriate that plaintiff would be required to reimburse the state for ADC benefits paid out on behalf of Lucas but not for those paid out on behalf of his other two children solely because plaintiff did not have physical custody of Lucas. To the extent that the minor child Lucas is being provided adequate support and care by the custodial parent, there is no reasonable societal need to saddle an indigent father with an onerous arrearage obligation. Under the circumstances of this case, we conclude that plaintiff's arrearages should be eliminated by the amount accumulated prior to February 5, 1985, the date on which plaintiff's two other children were transferred to the custody of their mother and the date on which ADC benefits to plaintiff were terminated. We remand for entry of an order consistent with this opinion.

Our decision is not based on MCL 400.63; MSA 16.463, since the trial court did not require plaintiff to meet his support obligation out of the funds he received through ADC. The trial court in this case adopted an approach consistent with Causley v LaFreniere, 78 Mich. App. 250; 259 N.W.2d 445 (1977), and Gonzalez v Gonzalez, 121 Mich. App. 289; 328 N.W.2d 365 (1982), and held that although plaintiff's support obligation accumulated during the period he received ADC benefits he would not be required to make up the arrearages until he obtained employment. In both Causley v LaFreniere, supra, and Gonzalez, supra, the noncustodial fathers were married and lived with their wives and children from those marriages. Both fathers' support obligations were minimal and the courts noted that the fathers had ample time within which to earn the small sums of money needed to satisfy their support obligations for their other children without jeopardizing their unemployment or welfare benefits. In neither Causley nor Gonzalez did this Court hold that a father's support obligation must continue without abatement even while he is on welfare. Instead, we looked to the circumstances of each case and evaluated the ability of the father to pay. We think that the facts in this case significantly differ from the facts presented in either Causley or Gonzalez because plaintiff, while unemployed, had physical custody of two minor children and was thereby limited in his ability to perform odd jobs in order to contribute $21 per week to the care of Lucas. We thus are not persuaded by defendants' reliance upon those two cases.

Affirmed in part, reversed in part and remanded for further proceedings consistent with this opinion. Jurisdiction is not retained.

T.M. BURNS, P.J., concurred.