What reimbursement means
Reimbursement is repayment of the other parent's share of a shared expense you paid up front. When one parent covers a cost that both are responsible for under the order or agreement, like an uncovered medical bill or an activity fee, they are typically owed the other parent's portion back.
Reimbursement is one of the most common flashpoints in co-parenting, because it relies on trust and memory unless it is documented. The fix is unglamorous but effective: log each expense with its date and amount, attach the receipt, record the reimbursement request, and keep a running ledger. Done this way, reimbursement stops being an argument and becomes arithmetic.
Example: you pay a $180 activity registration, log it with the receipt attached, and record that you requested the other parent's half. When they question it later, you have the date, the amount, the proof, and the request, not a disputed recollection.
How costs are split and which are reimbursable depend on your order, so keep the ledger factual and let the order settle what each parent owes.