TC 298: Additional Tax Assessment with Interest Computation Date

What the code actually does

IRS Document 6209 defines TC 298 as "Additional Tax Assessment with Interest Computation Date," Doc Code 54: "used to input an additional assessment of tax to a module (the IRS's record for one tax period within the account) which contains a TC 150. Generates assessment of interest from the interest computation date which must be included in the transaction... Otherwise same as TC 290." Mechanically, TC 298 raises the tax liability exactly like TC 290 does — the only structural difference is the mandatory interest computation date carried on the same transaction.

That date is not cosmetic. Ordinary assessments compute interest from the return's due date by default; TC 298 overrides that default with a specific date the IRS supplies, which is required precisely because the underlying facts (an amended return, a specific adjustment, a restricted-interest situation) call for interest to start running from somewhere other than the standard date.

The governing procedure moved — and the classification pointer was stale

The Internal Revenue Manual used to document Item 11 interest-computation-date entry under IRM 4.4.12, Examined Closings, Surveyed Claims, Partial Assessments, and Closings to Appeals. That subsection (4.4.12.5.20) has since been formally removed; the current live text of IRM 4.4.12 states the material "is now located in IRM 4.38.1.7.3.1.20, Item 11: Interest Computation Date." The successor section, fetched live this session, states plainly: a transaction "must include an interest computation date, entered in Item 11 of Form 5344," for exactly this code family.

Form 5344, Examination Closing Record, is the internal document Technical Services and Centralized Case Processing use to input an examination assessment. Item 11 on that form is where the examiner enters the interest computation date TC 298 or TC 308 then carries onto the transcript — so seeing either code with an unusual interest start date is not a data error; it reflects a deliberate entry made when the case was closed.

What this means for the account

If TC 298 appears, additional tax has been assessed and interest is running from a specific date built into the transaction — not automatically the return's original due date. Before agreeing to a balance-due figure the IRS states, confirm what interest computation date was actually used; a date earlier than expected means more interest has accrued than a simple due-date calculation would suggest, and a later date can mean less.

Because TC 298 "is not acceptable with TC 294 or 295" per Document 6209, its presence on a module rules out certain carryback-adjustment scenarios — useful context when reconciling a transcript that also shows carryback activity elsewhere.

What TC 298 gets confused with

The closest look-alike is TC 308, which performs the identical function — an additional assessment with a mandatory interest computation date — but specifically for an Examination or Appeals deficiency, and behaves "same as TC 300" rather than "same as TC 290." TC 298 can originate from ordinary return processing; TC 308 specifically signals the assessment came out of an examination or Appeals determination.

TC 298 is also not the same as a plain TC 290 with no interest computation date at all — the presence of that date is the entire reason TC 298 exists as a separate code rather than simply being posted as TC 290. Treating the two as interchangeable misses the deliberate interest-start-date override.

The practitioner's actual next step

Request the interest computation date actually used on the TC 298 transaction — it will not always match the return's original due date, and the difference changes the true balance owed.

If the module also shows carryback activity, confirm there is no conflicting TC 294 or 295 on the same document, since Document 6209 bars combining them.

Ask whether Form 5344 or its underlying case file is available if the interest computation date looks wrong — Item 11 on that form is where the examiner or processing employee entered it.

Pull the complete account history with the IRS Transcript Decoder to see whether TC 298 or its examination-track counterpart, TC 308, is the one actually present before assuming which process generated the assessment.