IRS Code 420 marks an opening record when a return has been referred or assigned to the Examination or Appeals function. It is not an additional assessment, a fraud determination, an audit outcome, or a deadline to respond. The indicator alone does not tell you which stage the case occupies, whether adjustments are proposed, or what correspondence was sent. Read the dated notice that accompanies the assignment before choosing your response path.
What Transaction Code 420 records
TC420 is an examination indicator that appears when the IRS opens an internal record for a return under Examination or Appeals review. According to the IRS Master File Transaction Codes publication, the code signals a referral or assignment, not a finding or adjustment (IRS Master File Codes). The transaction creates a control record; it does not by itself assess additional tax, freeze every future adjustment, or establish a response deadline.
A related code, TC424, marks an examination request indicator and serves a different administrative function. TC300, in contrast, represents an actual additional assessment resulting from Examination or Appeals work. Seeing TC420 on a tax account transcript confirms that some form of review has been initiated, but it does not reveal the scope of the inquiry, the items under scrutiny, or whether the taxpayer must furnish records by a specific date.
The IRS sends audit notification by mail. Use the actual letter to identify the tax period, reason for contact, requested response and official contact details. Different letters serve different stages; the code does not identify which letter applies. The code and the letter are separate artifacts: the code updates the internal system; the letter updates the taxpayer.
How to identify the actual stage
An examination indicator can accompany either a field examination, an office examination, or a correspondence audit. It can also appear when a case moves from Examination to Appeals after a taxpayer files a protest. The transcript alone does not distinguish these paths. Match the TC420 transaction date to the postmark or issue date on the IRS correspondence, then read the notice to confirm which function holds the case and what action is required.
A document request or conference invitation alone is not enough to classify the case. Read the issuing function, purpose and response instructions in the actual correspondence; resolve any uncertainty through the listed official contact. The IRS transcript codes lookup can help identify other transactions on the same account, but correspondence remains the authoritative source for stage, scope, and deadline.
Certain notices carry statutory deadlines that control your right to dispute proposed changes in Tax Court. A Notice of Deficiency has a separate petition period, generally 90 days or 150 days if addressed to a person outside the United States; see the notice-of-deficiency guide. An examination indicator may appear alongside deficiency-related entries, but the code itself does not trigger or extend that clock. When the audit statute of limitations remains open, the IRS retains authority to assess additional tax for the periods under review, and the expiration date may be extended by agreement or operation of law.
What TC421 reversal means
TC421 reverses a prior TC420 or TC424 indicator. The reversal closes the internal control record; it does not prove that the examination concluded with no change, that all proposed adjustments were withdrawn, or that every refund hold has been released. Read the reversal with the related account entries and correspondence to determine what changed.
After TC421 posts, locate any closing or adjustment correspondence and compare recorded assessments with the actual outcome described. Do not infer agreement merely from the reversal. If you expected a refund or credit to be released, look for IRS Code 846 indicating that the refund has been issued. The absence of TC846 alone does not identify a reason for nonpayment; use the complete account and official refund-status information.
Not all account activity is blocked while TC420 remains open. Certain systemic adjustments—including permitted zero-dollar TC290 entries—can post even when an examination indicator is present. Do not assume that every transaction will be frozen until TC421 appears.
Next checks after seeing the indicator
Once you confirm TC420 on the transcript, gather the correspondence, verify the tax period, and determine whether the notice requests records, schedules a conference, or proposes an adjustment. Compare the items listed in the notice to the return as filed, and identify the documents needed to substantiate each questioned item. If the notice names a specific examiner and provides a fax number or secure upload portal, prepare a transmittal log for each submission.
| Indicator | What it marks | What it is not |
|---|---|---|
| TC420 | Examination or Appeals assignment opened | An assessment, fraud finding, or deadline notice |
| TC424 | Examination request indicator | A closure or outcome determination |
| TC421 | Reversal of TC420 or TC424 control | Proof of no-change or full refund release |
| TC300 | Additional tax assessed by Examination or Appeals | An opening indicator or proposal |
When the correspondence references a specific code section or adjustment category—earned income credit verification, for example—identify the records the actual notice requests and the evidence relevant to the questioned issue. If the letter concerns Appeals, check its response requirements and preserve the relevant report, prior correspondence and any required submission evidence.
If no correspondence is available, confirm the tax period, review your retained mail and resolve the missing information through an appropriate official IRS contact route. The transcript date alone does not set a waiting period. When correspondence does arrive after the code posts, note the response deadline and calendar any intermediate milestones: records due, conference scheduled, or protest filing cutoff.
- [ ] Retrieve the IRS notice that corresponds to the TC420 transaction date
- [ ] Confirm the tax period, examination type, and items under review
- [ ] Identify the documents required to support each questioned line item
- [ ] Verify the response deadline and any scheduled conference date
- [ ] Check for TC300 assessments and compare amounts to any examination report
- [ ] After TC421 reversal, confirm that expected refunds or credits have posted
- [ ] Review the full transcript for related codes, offsets, and holds
Does TC420 mean the IRS has assessed additional tax?
No. TC420 marks the opening of an Examination or Appeals control record. An actual assessment appears as TC300, often with an explanation and amount. The indicator alone does not change your balance due or create a new liability.
Can account adjustments post while TC420 remains open?
Certain adjustments can post even when an examination indicator is present. Permitted zero-dollar TC290 entries are one example; the applicable processing rules contain exceptions. Other adjustments—refunds, for example—may be held pending the examination outcome, depending on the nature of the review and any related freeze codes on the account.
What should I do if TC421 appears but I received no closing letter?
TC421 closes the examination control record, but the absence of a closing letter means you should verify the outcome independently. Check the transcript for TC300 assessments, refund postings, and any new balance due. If the transcript shows no change and no refund, contact the examiner or Appeals officer named in the prior correspondence to request written confirmation of the closure and its result.
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