I work for an NPO which receives large numbers of paper check donations every week. The current process of recording the donations is tedious and done mostly on paper. Because most donations come from regular donors, we assign unique donor IDs, which makes it easier to generate end-of-year contribution reports (which our donors can use for tax purposes). However, most of our donors don't write their donor ID on their checks, which forces us to look up each donor ID manually.
To help streamline this process, I'm developing a small C# desktop app for internal office use. One of the features I'd like to provide is a quick lookup of donor IDs. A possible implementation could be to use a MICR reader to scan the checks, which would yield the donor's ABA routing and account number. I don't actually need that info for our records, but it could be used to do a quick lookup of the donor's ID. The routing and account number could be concatenated, hashed with something like SHA-512, then stored in a table which associates these hashes with donor IDs.
Would these one-way hashed routing/account numbers be considered PCI data, and therefore require PCI DSS compliance for our office?
NOTE: For reasons irrelevant to this post, we can't convert these checks to EFTs - which would be my personal preference.