Let's say that an individual filed his Federal 1040A and expects a decent refund. Let's say that this individual made a serious mistake in said tax return and only caught it after said filing was complete. Let's say that this mistake means that the individual would still get a refund, just smaller than originally projected. How does one follow up on this? Does one file a corrected / amended return IMMEDIATELY? Or does one wait until the return is processed and the original refund delivered, THEN file the amended / corrected return and mail in the appropriate payment? My concern for this hypothetical individual is that if one files said amended / corrected return too soon, the IRS will have a lot of room to create embarrassing blunders that make everything much too complicated. What say the resident experts?