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Electronic Interchange Reimbursement Fee, is an avoidable surcharge. Most EIRFs can be avoided, but there are ways to minimize these costly charges. EIRF is actually an interchange surcharge that Visa adds for certain downgraded transactions.
Say the AVS check wasn't perfect, or your software did some non-standard things.

It can add up, so make sure you find out what the real cause is.  It took me three months to track down the application that was causing a certain EIRF in my old position.  It ended up costing us over $2,000 per month!