Is there a way to backdate the avg cost. Our inventory is correct but our avg cost has been incorrect since February 1. Thanks in advance for any advice.

You can post a backdated inventory worksheet that will re-cost the item but not change the qty

If you are creating 2 transactions to correct the costing, they have to be on separate dates as average costing looks at Transaction dates to calculate the costing. Would also suggest doing this in off peak hours (like weekend)