It sounds like you received the generic letter that is sent to anyone who has a mistake on their tax return. The most common mistakes this year that cause you to get that letter are mistakes with the child tax credit or the recovery rebate credit. So look at lines 28 and 30 of your Form 1040. If you made a mistake when you were asked about the amount you received for advance child tax credit payments, or if you made a mistake when it asked if you received the 3rd stimulus payment of $1400 per person last year, that is why you got that letter.
TurboTax does not get any information from the IRS after you file your tax return, so no one at TT knows why your refund was less.
You have not mentioned any specific amounts. Sometimes we can make an educated guess as to the reason for your reduced refund if you mention specific amounts--for example if your refund was short by $1400 per person---it is likely to be a mix up regarding the 3rd EIP payment. If you received the 3rd stimulus check of $1400 per person in 2021 then you got letter 6475 from the IRS about it. You needed to enter the amount you received. If you already received that money then line 30 on your Form 1040 should have been blank.
If it is short by $1800 or $1500 or a multiple of that amount --- maybe a mixup regarding the advance child tax credit payments. If you received monthly child tax credit payments of $250 or $300 per month between July and December of 2021, then you got letter 6419 from the IRS, and you were required to enter the amount of the advance payments. Only the remaining amount of the CTC should have been on line 28 of your Form 1040.
The IRS knows how much they sent to you for the 3rd stimulus check and they know how much they sent for advance child tax credit payments. If you answered something incorrectly on your tax return then the IRS made a correction that resulted in a reduced refund for you.
The IRS will send you a letter that explains why your refund was reduced. Meanwhile it might help you to check your own bank account for deposits of $1400 per person sometime after mid-March of 2021, or for deposits of $250 or $300 per child from July to December, and check your online IRS account.
https://www.irs.gov/payments/your-online-account
https://blog.turbotax.intuit.com/tax-refunds/why-is-my-tax-refund-not-what-i-expected-49240/
https://www.irs.gov/newsroom/questions-and-answers-about-the-third-round-economic-impact-payment-top...
If you need to trace a payment that the IRS says has been issued to you, mail or fax a completed IRS Form 3911, Taxpayer Statement Regarding Refund.
Updated IRS FAQ about recovery rebate credit
https://www.irs.gov/pub/taxpros/fs-2022-27.pdf
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
