Is a charity required to send an acknowledgment to the matching gift company for sending a matching gift check?
Not unless you want to keep good relations with your donors. If a donor receives no goods or services in return for the gift, a charity is not legally required to acknowledge a gift. But if the gift is $250 or more, a donor may not claim a charitable contribution deduction without having a contemporaneous acknowledgment from the charity stating the amount of the gift, whether any goods or services were provided in return, and, if so, the value thereof. It wouldn’t make for good donor relations if your donor lost a deduction because you failed to acknowledge the gift properly.
Some matching gifts may come from corporate foundations, which don’t need an acknowledgment for deduction purposes because they treat the payments as a distribution and do not claim a deduction. Some matching gift programs may require receipts as part of the program, but that would be an internal corporate policy, with which you would be required to comply only if you wish to be eligible for more gifts.
Wise charities have adopted a policy of acknowledging – and thanking – the donor of every gift, no matter what the size and no matter whether the donor needs it or not. Doing anything else is foolish.