IRS has known for months that this could happen, and Congress has talked to them about how much lead time they need to change the system.  Isn't that one reason e-filing starts later than usual, this year? Can you remember any year it started this late?  IRS will probably moan and groan about how they can't do it on original returns, they have to make another run through the data to find the people who qualify for higher payments, but they have experience with that.  Look at all the rebates paid in the last three years -- not to mention the last 30 years.