In his sole assignment of error, plaintiff contends the lower court erred in concluding as a matter of law that it should not forgive the arrearage of $2,928.50. We disagree.

This Court has previously held that the noncustodial parent is not entitled as a matter of law to a credit against accrued ar-rearage in child support for expenses incurred while the child was with the noncustodial parent. Goodson v. Goodson, 32 N.C. App. 76, 231 S.E. 2d 178 (1977). Each case must be decided upon its own facts, and the guiding principle is whether an injustice would exist if a credit is not given. The decision to allow, or disallow, such credit is a matter within the discretion of the trial judge. Jones v. Jones, 52 N.C. App. 104, 278 S.E. 2d 260 (1981) and Lynn v. Lynn, 44 N.C. App. 148, 260 S.E. 2d 682 (1979).

While the ruling on this point is contained in the conclusions of law, the wording that, “the Court should not forgive” manifests that the trial judge did not misapprehend his discretionary authority to grant such relief.

In Evans v. Craddock, 61 N.C. App. 438, 300 S.E. 2d 908 (1983), this Court held the trial court did not abuse its discretion in denying the noncustodial father credit against his child support obligation for a four to five week period during which the minor child actually resided with the father. Similarly, in Gibson v. Gibson, 68 N.C. App. 566, 316 S.E. 2d 99 (1984), this Court rejected plaintiff s argument that substantial visitation with the noncustodial parent relieves the custodial parent of some of the fixed expenses of the child and held:

The fact that a child spends a certain amount of time with one parent does not necessarily mean, as plaintiff would have us to assume, that his reasonable and necessary living expenses are incurred proportionally.

The pattern of unilateral reduction in support payments had continued in the instant case for over two years before plaintiff moved for modification of the 1977 consent order. As this Court stated in Lynn v. Lynn, supra, “[a] party bound by court order to make payments to another party may not, without risk of violation, unilaterally modify the form of compensation provided in the order.”

*728Although plaintiff argues that the facts here justify credit for the time the child spent with him beyond the time periods originally contemplated by the parties, we find no abuse of discretion by the trial court in not giving him that credit.

The judgment appealed from is

Affirmed.