People look at their transcript and see interest charged on a few specific dates, then assume interest only runs on those dates. It does not. Interest runs continuously. The transcript lines are the moments the IRS formally assessed what had accrued.
The legal rules
IRC 6601(a) imposes interest at the underpayment rate under IRC 6621 on any tax not paid by the last date prescribed for payment, "for the period from such last date to the date paid." IRC 6601(b)(1) says that last date is determined without regard to any extension of time for payment or any installment agreement. So an extension to file or a payment plan does not stop interest.
IRC 6622(a) requires that interest be compounded daily. IRC 6601(e)(1) treats interest as tax: it is paid on notice and demand and assessed, collected and paid in the same manner as taxes. And IRC 6601(g) lets the IRS assess and collect interest at any time during the period within which the underlying tax may be collected.
TC 196: interest assessed
Document 6209 titles TC 196 "Interest Assessed" and lists when the computer generates it: "at First Notice time; upon issuance of an Account Adjustment Notice resulting from posting of TC 290/300; posting of TC 680 (Designated Payment of Interest), or if a credit condition exists in the module: at TDA/BAL DUE time; and upon issuance of Credit Reversal Notice (CP 60)."
That list explains the jumps. Interest is assessed when a notice goes out, when an adjustment notice issues, and at certain other trigger points. Between those points it accrues without being assessed. The accrued interest line at the top of the transcript shows the unassessed portion, calculated to a stated date.
So a transcript might show a TC 196 at the first notice, another after a TC 290 adjustment, and a large accrued interest figure in the header. All three are interest on the same tax. Add the assessed lines to the accrued figure to see the whole picture as of that date.
TC 336: interest on an exam deficiency
Exam assessments get their own interest code. Document 6209 describes TC 336 as computer-generated interest "on additional tax or deficiency assessed upon posting of an Examination Adjustment (TC 300 with Doc. Code 47) and issuance of the adjustment notice."
Exam interest is usually large because it runs from the original due date of the return, not from the date of the audit. A deficiency assessed years after the return was due carries interest for all of those years. See TC 300.
There is one statutory pause worth knowing for agreed exams. IRC 6601(c) says that if a waiver of restrictions on assessment is filed under IRC 6213(d) and notice and demand is not made within 30 days after the waiver is filed, interest is not imposed for the period beginning after that 30th day and ending with the date of notice and demand.
Abatements of interest
| Code | What it abates | When it generates |
|---|---|---|
TC 197 | Prior TC 190 or TC 196 interest | When postings cause interest assessed to exceed interest due, for example an abatement of tax |
TC 337 | Prior TC 190, TC 196 or TC 336 interest | When an examination TC 301 posts |
TC 341 | Prior TC 190, TC 196, TC 340 or TC 336 | Manual restricted interest abatement |
When tax comes off, interest computed on that tax should come off with it. If you see a TC 291 or TC 301 with no TC 197 or TC 337 nearby, it is worth checking whether the interest was recomputed.
Restricted interest: TC 340
Sometimes the computer cannot be trusted to compute interest, and an IRS employee computes it by hand. Document 6209 describes TC 340 as "restricted interest which must be manually computed" and warns that after it posts, "interest is not computed or abated by computer for the applicable Tax Module." TC 342 removes the restriction and lets the computer recompute normal interest.
Restrictions show up in special situations. Document 6209 says a TC 150 with condition code Z, used for combat zone cases, generates a TC 340 for zero amount and turns on the debit restricted interest indicator. A military deferment, TC 500, also generates a TC 340, and an accepted offer, TC 780, prevents the computer from generating interest.
If your account has a restricted interest indicator, the accrued interest figure on the transcript may not be reliable. Ask the IRS for a manual computation before you rely on it for a payoff.
Designated interest payments: TC 680
Document 6209 defines TC 680 as a designated payment of interest, input "to pay assessed and/or unassessed interest due without tolerance application." Paying it generates a TC 196 to the extent the payment covers unassessed interest. Any amount over the total interest due applies to tax and penalty. Document 6209 also lists TC 680 among the events that can generate a TC 570 hold if the payment creates a credit balance of $5 or more.
Interest the IRS owes you
Interest runs the other way too. Document 6209 describes TC 776 as computer-generated interest due "when a Tax Module is overpaid as the result of a credit or an abatement," and TC 770 as manually computed credit interest. TC 777 reverses generated credit interest when a refund check is returned or cancelled.
When you have an overpayment on one year and a balance on another for overlapping periods, interest netting may apply. Document 6209 says an interest netting TC 777 is generated with 999 in the Julian date of the DLN, and lists TC 971 action code 355 to indicate that manual interest netting computations were performed. See TC 846: Refund Issued.
Interest suspension codes
Some interest is suspended by statute. Document 6209 lists TC 971 action code 064, "Section IRC 6404(g) interest suspension 3305 Date used for interest computations," and action code 164 to "identify liability that has been disqualified from IRC 6404(g) interest suspension." If you see either code, the interest computation on that year was run through the IRC 6404(g) suspension rules, and it is worth asking how the dates were set.
Disaster relief can affect interest too. Document 6209 describes TC 971 action codes 086 and 087 for disaster relief and a disaster freeze that "causes unique penalty and interest processing."
The 21-day rule after notice and demand
One timing rule can save real money. IRC 6601(e)(3) says that if notice and demand is made for payment of an amount and that amount is paid within 21 calendar days after the date of the notice and demand (10 business days if the amount is $100,000 or more), interest on the amount so paid is not imposed for the period after the date of the notice and demand.
In practice, that means paying a notice balance within the window stops interest on that amount as of the notice date. It is one more reason to read the date on the notice and the matching TC 971 notice line on the transcript, and to act on the notice, not on the transcript date you happened to see weeks later.
Remember also that the header's accrued figures are computed to a stated date. If you are calculating a payoff, ask the IRS for a payoff figure good through a specific date rather than adding up the transcript yourself.
Reading interest correctly
- Total all
TC 196andTC 336lines. That is assessed interest. - Add the accrued interest figure from the header. That is the full interest as of the stated date.
- Subtract any
TC 197,TC 337orTC 341abatements. - Check for
TC 340restrictions before trusting the computed figures. - Look for credit interest,
TC 776, on years with overpayments.
Interest is rarely the thing you can argue away. It follows the tax. Reduce the tax, or pay it, and the interest follows. Understanding the codes keeps you from paying the wrong number or arguing about the wrong line.