TC 298: Additional Tax Assessment with Interest Computation Date

What the code actually does

IRS Document 6209 (the IRS’s reference guide to its data-processing codes) defines TC 298 as "Additional Tax Assessment with Interest Computation Date," Doc Code 54 (a data processing adjustment): "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.

Form 5344 Item 11 is TC 308's procedure, not this code's

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." IRM 4.38.1.7.3.1.21.2 states that TC 308, the examination-track twin of this code, "must include an interest computation date, entered in Item 11 of Form 5344." The Item 11 section names TC 304, 305, 308 and 309. It does not name TC 298, so that section does not govern this code's date.

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 308 carries onto the transcript. TC 298 is a Doc Code 54 adjustment under Doc 6209, not an examination closing, so Form 5344 is not where its date comes from. On either code an unusual interest start date is usually a deliberate entry, not a posting glitch, but the entry can be wrong; check it against the adjustment document.

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, ask the IRS what interest computation date it 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, on business accounts, 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 people mistake TC 298 for

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.

What to do next

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 on business accounts.

If the interest computation date looks wrong, ask for the adjustment document behind the TC 298. Form 5344 Item 11 holds that date only for the examination codes TC 304, 305, 308 and 309.

Run the account history the client supplies through 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.