TC 420: Examination Indicator

What the code actually does

TC 420 records that a return has reached Examination. IRS Document 6209, Section 8A describes it as "computer generated at SC when opening record is posted," indicating "that return has been referred to the Examination or Appeals Division," and adds the sentence that distinguishes it from its sibling: "the return has been assigned in the Examination or Appeals Division."

Assignment is the difference. A referral is a case selected; an assignment is a case with someone working it. That is why the two examination codes are not interchangeable even though IRM 21.5.6.4.24 treats them as one trigger for freeze purposes.

The freeze does not freeze the account

The -L freeze is one of the more misleadingly named things on a transcript, and the IRM says so directly. IRM 21.5.6.4.24, in its current revision, states: "The -L (Open Examination Indicator) freeze is set when a Transaction Code (TC) 420 or TC 424 posts to an account that has been referred to Examination. It does not freeze the account."

Money is not held because of it. Refunds are not stopped by it. A client whose refund has not arrived on a year carrying a TC 420 is being held up by something else on the module — a refund-hold code, an additional-liability freeze, an offset — and looking to the examination indicator for the explanation will waste the call.

What the -L condition does do is route the work. The IRM directs employees to research the examination procedures "before making adjustments to the account," and points to the claims, math-error and examination-issues chapters. It is a stop sign for account technicians, not a hold on the taxpayer’s money.

What it actually blocks: the adjustment codes

The real operative effect is in Doc 6209, and it is specific. "Generally, if TC 420 is unreversed, TC 290, 291, 298 and 299 will unpost unless Priority Codes 1, 5, 6, 7, or 8 present."

Unposting is not a delay; it is a rejection. An ordinary TC 290 adjustment keyed against a module with an open TC 420 will not take. This is the mechanism behind a familiar and frustrating pattern: a client’s straightforward correction is agreed on the phone, nothing appears on the account, and nobody can say why. The year is under examination, and the adjustment bounced.

There are documented exceptions. Doc 6209 records that "TC 290 with zero amount, 294 or 295 will post" — so freeze releases and the tentative-carryback codes get through, as do adjustments carrying one of the listed priority codes. Knowing which of those applies is the difference between resubmitting correctly and resubmitting identically.

Doc 6209 adds one more thing the code does not do: the “module will not be removed from MF.” The year stays on the master file for as long as the indicator is open, which is why an examined period can persist on transcripts long after a taxpayer expected it to age off. That persistence is a feature of the examination rather than evidence that something else is outstanding.

What TC 420 gets confused with

It gets confused with TC 424, which is the earlier signal — a return referred to Examination and opened in inventory, often visible before this code posts. A TC 424 alone may still resolve without a taxpayer ever hearing from anyone; a TC 420 means the case has been assigned. Treating them as one event overstates the position of a client whose return was merely selected.

It is also confused with underreporter activity. TC 922 is document matching, a different program with a different manual and a different notice path, and Doc 6209 records that an examination request code "can also be generated for IMF when an IRP Underreported Case is referred to Exam" — so the two can appear in sequence. Which one governs at any moment determines what the client is actually facing.

Finally, the reversal codes are not equivalent. An examination that closes with a deficiency generates the reversal automatically off the TC 300 assessment when the disposal code is one of the examined-closing values; a bookkeeping reversal of the earlier request code is a different transaction that means only that the request no longer stands.

The practitioner’s actual next step

Stop attributing a stopped refund to this code, and find the transaction that is actually holding the money.

Before submitting any adjustment on the year, establish whether it will unpost, and whether a priority code or the zero-amount form is the right route.

Distinguish assignment from referral by checking whether the earlier request code is also present and when each posted.

Watch for the assessment and its automatic reversal together — an assessment posting without the indicator clearing suggests a partial rather than a closed case.

Read the whole module in sequence rather than code by code, which is what the IRS Transcript Decoder is for.