On the paper
Read which items the notice says are under review and whether it asks you for anything at all.
Check whether the paper asks for documents. Most of these letters ask for nothing and simply announce the hold. A version that does ask, or that encloses a form, is a different situation from the routine hold, and the request is the part that has to be answered.
Find the date printed on your notice or letter. The paper notice and the current official IRS instructions control, even where this page differs.
CP05
The IRS page for CP05, checked September 10, 2026, says the IRS is verifying income, withholding, tax credits, or business income and that no action is required if you filed the return.
It says to allow up to 60 days before reaching out, and not to call until 60 days after the notice date and only if you have not received the refund or heard from the IRS by then.
In practice CP05 is the automated hold. Nothing is being proposed, no adjustment has been made, and the file may close with the refund released and no further mail.
Letter 4464C
Letter 4464C carries the same message in letter form. The IRS page for it, checked September 10, 2026, says the letter concerns income and withholding verification and that no immediate action is required if you filed the return.
It gives the same instruction on timing: do not call until 60 days after the letter date, and only if you have not received the refund or heard from the IRS by then. If nothing has arrived after 60 days, it names the telephone number to use.
Because the two are the same review under two labels, this page treats them together. A reader holding either one has the same question and the same answer.
What the review is checking
The items the IRS names are income, withholding, and credits, which are the figures it can compare against the information returns employers and payers filed for the same year.
Withholding is the most common source of a hold. Where a payer filed late, filed a corrected form, or reported under a different identification number, the return and the IRS record disagree until the payer's filing catches up.
The review is not an examination and does not open the return to a broader look. It ends either with the refund released or with a further notice describing something specific.
Where this notice comes from
These notices come from return processing, before any examination function sees the file. The refund is held while the automated matching finishes.
The 60-day instruction is about IRS capacity rather than about your rights. Calling earlier generally produces the same answer the letter already gave, and it does not move the file.
If the review does find something, the next document is specific: a request for records, a proposed change such as CP2000, or an examination notice. Until one of those arrives there is nothing to answer.
General next steps
- Read the notice for any actual request, and answer only what it asks for.
- Review your own copy of the return for errors while the review runs, and consider an amended return if you find one.
- Note the date on the paper and count 60 days from it before calling the IRS.
Timing
The 60 days come from the IRS pages for CP05 and Letter 4464C, both checked September 10, 2026, and they describe when to call rather than a period for you to act in. Neither page sets a response deadline, because neither notice ordinarily asks for a response. The date printed on the notice controls; do not calculate a deadline from this page.
What CP05 and Letter 4464C does not mean
A hold is not an audit and not a denial. The IRS has not proposed a change or questioned a specific item on the record it sends you. It also does not mean the refund is lost, and it does not mean you did anything wrong; the review is frequently caused by a payer's filing rather than by yours.
What this page cannot tell you
This page cannot tell you when a specific refund will be released or what the IRS is checking on your account.
Official sources
If anything on this page differs from your notice or from current IRS instructions, follow the notice and the IRS.
Common questions
Is CP05 different from Letter 4464C?
They are the same review in two formats. Both say the IRS is verifying income, withholding, and credits, both hold the refund while that runs, and both tell you not to call until 60 days after the date on the paper.
Do I need to send anything?
Not unless the paper asks. Both pages say no action is required if you filed the return. If your copy encloses a request or a form, that request is the exception and it should be answered.
Does interest accrue on a refund the IRS is holding?
The Internal Revenue Code provides for interest on refunds not paid within a set period after filing. Whether it applies to a particular refund depends on when the return was filed and when the refund is issued.
Can I file an amended return while the review runs?
The IRS suggests reviewing your return for errors and filing an amended return if you find one. An amendment filed during the review may extend the processing time.