A Tax Professional at your office states that record reconstruction is not important unless the taxpayer is claiming a refundable credit. The BEST reply would be: This is incorrect. ANY time a taxpayer does not have adequate records, a thorough reconstruction must be done. This is incorrect. It's not as important if the taxpayer isn't claiming a refundable credit, but you should still do a cursory reconstruction. This is correct. You can accept the taxpayer's best guess for their income and expenses as long as they're not claiming a refundable credit. This is correct. Record reconstruction is only important if the taxpayer is claiming a refundable credit.