This is the first time I can ever recall one of my clients receiving a cp05 letter. The return was electronically filed and accepted on April 16th. It is a married filing joint return and they have four children. Standard deduction. With the four children they do have a large child tax credit and I think that is why the return is being held up. Other than that they have a small credit for child care and a small retirement contribution credit. The letter says that they are reviewing the return and they list a few items that they may be looking at ; income , , ,income tax withholding, and or tax credits. Has anyone else received this letter? What is also interesting is the taxpayer received a separate letter and his spouse received the same letter. I do not know why they split the letters up since they have always been married to each other and there are no issues there.