IRS Collection Statute Expiration Date (CSED): Practitioner Reference Guide

The Collection Statute Expiration Date is one of the most consequential numbers in IRS collection representation. Get it wrong and you may recommend a resolution strategy that inadvertently extends the IRS's collection window, advise a client that a liability has expired when tolling events have pushed the deadline forward, or miss the strategic opportunity that a correctly computed CSED creates. This guide is written for enrolled agents, CPAs, and tax attorneys who need a precise, citation-anchored reference for CSED computation, tolling analysis, transcript reading, and PPIA strategy.

All procedures, statutory citations, and regulatory guidance referenced in this guide must be verified at IRS.gov and under the current versions of the applicable IRM provisions before being relied on in any specific client matter. IRM provisions are updated periodically; any procedural detail printed here may be superseded.

This guide is for informational purposes only and does not constitute legal or tax advice. CSED computation is fact-specific and subject to IRS verification.

Section 1: The 10-Year Rule Under IRC 6502

IRC 6502(a)(1) provides the IRS with a 10-year window from the date of assessment to collect a tax liability by levy or by a proceeding in court. Once that window closes, the IRS loses its enforcement authority for that specific assessment. No levy. No lawsuit. No further demand. This is the Collection Statute Expiration Date.

The collection period addressed by the CSED is distinct from the assessment period. The assessment statute under IRC 6501 governs how long the IRS has to assess a liability in the first place; only once an assessment is recorded does the 10-year collection clock under IRC 6502 begin. Practitioners analyzing a client's total exposure must evaluate both windows separately. For the assessment side, see our IRS audit statute of limitations guide (IRC 6501).

"Date of Assessment" Defined

The date of assessment is the date the IRS officially records the tax liability on its books: not the date the return was filed, not the return due date, and not the date a notice was issued. Assessment occurs when an IRS assessment officer signs the summary record of assessments. Practitioners track the assessment date through the transaction codes on the IRS Account Transcript:

• TC 150: Original return processed and assessed. The date next to TC 150 is the primary CSED start date for that assessment. When a Substitute for Return (SFR) was filed by the IRS, the TC 150 date from the SFR starts the CSED; see our SFR practitioner guide for the displacement workflow.
• TC 300: Additional tax assessed as a result of an examination or audit. Separate CSED starts from this date.
• TC 290: Additional tax assessment after the original return (for example, a math error correction or a subsequent adjustment). Separate CSED from this date.
• TC 240: Penalty or interest assessment. A penalty assessed separately from the underlying tax carries its own CSED running from the TC 240 date, which may differ materially from the TC 150 or TC 300 date.

Estate Tax CSED (Form 706)

IRC 6502 applies equally to estate tax assessments. For estate tax returns filed on Form 706, the CSED begins on the date of assessment of the estate tax liability, not the estate tax return due date or filing date. Practitioners handling estate tax collection matters must pull the estate tax account transcript and identify the TC 150 assessment date to compute the applicable CSED.

Section 2: Multiple Assessments and Overlapping CSEDs

A single tax year commonly generates more than one assessment, and each assessment carries its own independent 10-year CSED. Practitioners who compute only the TC 150 CSED will miss the full collection picture.

How Overlapping CSEDs Arise

Consider a 2019 tax year with the following transcript entries:

• TC 150 dated September 2020: original return assessment. CSED runs 10 years from September 2020.
• TC 300 dated March 2023: audit examination assessment of additional tax. A separate CSED runs 10 years from March 2023.
• TC 240 dated June 2023: accuracy-related penalty assessed. A CSED for that penalty runs 10 years from June 2023.

In this example, the same taxpayer for the same tax year has three separate CSED dates, each governing the IRS's authority to collect that specific component of the total liability. The later assessment dates extend the IRS's collection window for the additional amounts assessed in the examination, even if the original TC 150 CSED is nearing expiration.

Penalty Assessments Warrant Separate Tracking

Penalty assessments under TC 240 frequently carry assessment dates that are months or years after the underlying tax assessment. In multi-year cases involving Trust Fund Recovery Penalty assessments (IRC 6672), the CSED for the penalty runs from the TFRP assessment date, which may be years after the employment tax periods at issue. Practitioners must track each TC 240 entry separately and compute its independent CSED.

Section 3: Tolling Events That Pause the CSED Clock

Certain events suspend the running of the CSED for the duration of the event, plus any statutory extension period that follows. Every day the clock is suspended is a day added to the end of the collection window. Practitioners must identify every tolling event on the transcript before computing the final CSED.

Offer in Compromise (OIC) Pending

The CSED tolls from the date the IRS receives the OIC until the date of rejection or withdrawal, plus 30 days after rejection. If the taxpayer appeals a rejection to the IRS Office of Appeals, tolling continues during the appeals consideration period as well. Statutory authority: IRC 7122(e).

If the IRS returns an OIC as unprocessable (because the taxpayer is not in filing compliance, the submission is incomplete, or the filing fee is missing), tolling runs from receipt to the date of the return notice, not to 30 days after. The distinction between a formal rejection (which adds 30 days) and a return for unprocessability is significant: practitioners should confirm in writing whether the IRS action was a rejection or a return.

If the OIC is accepted and the taxpayer satisfies the agreed amount, the remaining liability is compromised and collection authority terminates on a different basis entirely. For the full OIC framework, see the IRS Offer in Compromise practitioner guide.

Collection Due Process (CDP) Hearing

The CSED tolls from the date the IRS receives the CDP hearing request until the date of the Notice of Determination issued by the IRS Office of Appeals, plus 90 days. If the taxpayer files a petition with the Tax Court for review of the Notice of Determination, tolling continues until the Tax Court decision becomes final, plus 90 days. Statutory authority: IRC 6330(e)(1).

CDP hearings are frequently used as a collection defense tool, but practitioners must weigh the additional tolling the CDP request adds to the CSED before filing. In cases where the CSED is imminent and the taxpayer's primary goal is to let the clock run, filing a CDP request may extend the IRS's collection window by a year or more. For the full CDP framework, including equivalent hearing rights and Levy CDP vs. Lien CDP distinctions, see the IRS Collection Due Process hearing practitioner guide.

Bankruptcy Automatic Stay

The filing of a bankruptcy petition triggers the automatic stay under 11 U.S.C. 362, which suspends most IRS collection activity. The CSED tolls from the petition date until the automatic stay is lifted or the case is dismissed or closed, plus an additional 6 months. Statutory authority: IRC 6503(h).

The 6-month extension after the stay lifts is mandatory and applies regardless of how quickly the bankruptcy case resolves. A Chapter 7 case that closes in 4 months still adds 4 months plus 6 months to the CSED. Practitioners who advise bankruptcy as a collection resolution tool without accounting for the CSED impact may inadvertently extend the IRS's collection window by 6 months or more beyond what the bankruptcy itself consumed. For the discharge analysis (the three-prong 3-year, 2-year, and 240-day tests under IRC 523) and Chapter 7 versus Chapter 13 strategy, see our Bankruptcy and federal tax debt discharge guide.

TAS Taxpayer Assistance Order (TAO)

When the Taxpayer Advocate Service issues a Taxpayer Assistance Order requiring the IRS to take or refrain from a specific collection action, the CSED tolls for the period the TAO is in effect. Statutory authority: IRC 7811. TAO-based tolling is less common than OIC or bankruptcy tolling but must be captured if a TAO was issued in the taxpayer's history.

Form 900 (Voluntary CSED Waiver)

A taxpayer who signs Form 900 voluntarily extends the CSED to the date specified on the form. This is not a statutory tolling event in the same sense as OIC or bankruptcy; it is a contractual extension. Once signed, the extension is irrevocable for the period stated. The full Form 900 analysis is covered in Section 8 of this guide.

Combat Zone Service

Military personnel deployed to a combat zone designated under IRC 7508 receive additional time to perform tax obligations, and the CSED tolls during the combat zone service period plus 180 days after the taxpayer's last day in the combat zone. Statutory authority: IRC 7508. Practitioners handling cases involving military taxpayers must verify whether any combat zone deployment occurred during the CSED period.

Wrongful Seizure Proceedings and Release of Levy Pending Court Review

Where the IRS releases a wrongful levy or seizure under IRC 6343(b) and court proceedings are initiated, the CSED may toll during the pendency of those proceedings. Similarly, where a levy is released pending review by a court, the clock may be suspended. These situations arise less frequently than OIC or CDP tolling, but practitioners handling levy or seizure disputes should verify whether any court proceedings have altered the CSED calculation.

Innocent Spouse Proceedings

Most innocent spouse claims under IRC 6015 do not independently toll the CSED. However, if the taxpayer files for bankruptcy in connection with or during innocent spouse proceedings, the bankruptcy automatic stay tolling under IRC 6503(h) applies. Practitioners should not assume that filing Form 8857 extends the CSED; it does not, absent a separate tolling event such as a bankruptcy filing or a CDP request arising from the same collection activity.

Section 4: What Does NOT Toll the CSED

Knowing what does not toll the CSED is as important as knowing what does. Several common resolution and administrative actions leave the CSED clock running, which is either strategically useful (CNC, standard installment agreement approaching expiration) or simply a non-issue that practitioners sometimes overestimate (administrative appeals, penalty abatement requests).

Currently Not Collectible (CNC) Status

When the IRS places an account in CNC status (Transaction Code 530), the IRS suspends active collection: no levies, no wage garnishments, no collection demands. The CSED, however, continues to run without interruption. There is no statutory basis for CNC status to toll the collection statute; it is an administrative suspension of collection activity, not a legal event that affects the 10-year clock.

This is the feature that makes CNC strategically valuable for certain clients: a taxpayer in CNC with a CSED expiring in two years will watch the liability become legally uncollectible without making any payment, assuming the CSED calculation is correct and no tolling events occur during that window. For the full CNC framework, including hardship standards, ACS vs. Revenue Officer procedures, and re-activation triggers, see the Currently Not Collectible practitioner guide.

Standard Installment Agreement

A standard installment agreement does not toll or extend the CSED. The IRS has no statutory authority to toll the CSED simply because the taxpayer is in an installment agreement, and the agreement itself does not extend the collection window. The CSED clock runs throughout the term of the agreement while the taxpayer makes monthly payments. The agreement prevents levy during its term (the IRS will not issue a levy while the taxpayer is current on an active IA), but the statute is unaffected.

A practitioner whose client has 18 months left on the CSED and enters a standard IA will find that the CSED expires 18 months later, regardless of whether the agreement is paid in full. If the balance is not retired by then, the remaining unpaid balance of the original assessment becomes legally uncollectible at CSED expiration.

Partial Payment Installment Agreement (PPIA)

A PPIA also does not toll the CSED. Like a standard IA, the PPIA prevents levy while the agreement is active and current, but does not affect the 10-year collection clock. The PPIA is specifically designed to exploit this: payments are structured at an amount the taxpayer can afford, set deliberately below the level needed to retire the full balance before CSED expiration. When the CSED arrives with a balance remaining, that balance becomes legally uncollectible.

This is a distinct and important difference from an OIC. An OIC tolls the CSED during the consideration period, whereas a PPIA does not. When comparing PPIA to OIC as resolution strategies, practitioners must model the CSED impact: the OIC toll may extend the IRS's collection window by the entire duration of the OIC review process (often 12 to 24 months), while the PPIA leaves the clock running.

Non-CDP Administrative Appeals

Filing a Collection Appeals Program (CAP) request or submitting a written protest to the IRS Office of Appeals on a non-CDP matter does not toll the CSED. There is no statutory authority for administrative appeals consideration to pause the 10-year clock. Practitioners who file a CAP request as a delay tactic should be aware that the CSED continues to run during that period.

Penalty Abatement Requests

Requesting first-time abatement or reasonable cause penalty abatement does not toll the CSED. The abatement request is an administrative request to reduce the balance; if granted, it reduces what the IRS can ultimately collect, but the 10-year window for collecting whatever remains is unaffected by the pendency of the abatement request.

Section 5: Reading CSED from IRS Account Transcripts

The Account Transcript is the authoritative document for CSED analysis. Practitioners who rely on balance-due notices, online account summaries, or IRS-provided verbal CSED dates without independent transcript verification are operating with incomplete information. The following transaction codes are the building blocks of CSED computation.

TC 150: Original Assessment

TC 150 indicates that the original return has been processed and the tax liability has been assessed. The date next to TC 150 on the Account Transcript is the primary assessment date from which the first CSED clock runs. This date is the starting point for computing the base 10-year CSED before any tolling adjustments.

TC 300: Audit (Examination) Assessment

TC 300 reflects additional tax assessed following an IRS examination. The assessment date for TC 300 starts a separate, independent CSED clock for the additional tax assessed in the examination. If the examination produced a TC 300 three years after the original TC 150 assessment, the IRS has until three years after the TC 300 date to collect the additional examination tax, regardless of what has happened to the TC 150 CSED.

TC 520: CSED Tolling Begins

TC 520 is the transcript signal that a CSED suspension event has started. The date next to TC 520 is the date the toll begins. The TC 520 entry includes a closing code that identifies the reason for the toll:

• Closing code 60 or 61: bankruptcy-related suspension.
• Closing code 76 or 77: OIC pending.
• Closing code 78: CDP hearing or innocent spouse relief.
• Closing code 81 or 82: suit or court proceedings.

The specific closing code matters for understanding the nature and duration of the toll. Verify current TC 520 closing code definitions under the applicable IRM at IRS.gov, as code meanings and assignments may change.

TC 550: CSED Tolling Ends

TC 550 closes the tolling period opened by TC 520. The date next to TC 550 is the date the toll ended. The "memo amount" or cycle field associated with TC 550 reflects the number of days added to the CSED as a result of the tolling event. To compute the adjusted CSED for an assessment that was tolled, take the raw 10-year CSED (base assessment date plus 10 years) and add the number of days reflected in each TC 550 entry.

Where multiple TC 520 and TC 550 pairs appear on the transcript (for example, an OIC followed by a CDP hearing followed by bankruptcy), the total days added to the CSED is the sum of each TC 550 toll period. These must be added sequentially, not concurrently, and the computation must account for any statutory extension periods (such as the 30 days added after OIC rejection or the 6 months added after bankruptcy).

TC 971 with Action Code 043

TC 971 with Action Code 043 indicates that an Offer in Compromise has been submitted. This entry appears near the time the OIC was received by the IRS and confirms that OIC-based tolling is in play for the assessment periods covered by the offer. When a TC 971 Action Code 043 appears without a subsequent TC 550 closing the toll, the OIC may still be under consideration or the transcript may be incomplete.

Transcript Completeness for Older Periods

IRS online account transcripts accessible through IRS.gov may not display all TC 520 and TC 550 entries for older tax periods, generally those predating 2010. For pre-2010 periods or any case where online transcript data appears incomplete or internally inconsistent, practitioners should request the Account Transcript by mail (Form 4506-T) or via fax under IRM 5.1.19. The MFTRA-X (Master File Transcript) provides the most complete transaction code history and is the appropriate document for complex multi-event CSED analysis.

Section 6: PPIA as a CSED Management Strategy

A Partial Payment Installment Agreement is an installment agreement under which the taxpayer makes monthly payments set at an amount determined by a financial analysis using IRS Collection Financial Standards, rather than at the amount needed to fully retire the liability before the CSED. Because the PPIA does not toll the CSED, the 10-year clock continues to run throughout the agreement. If the balance is not fully paid by CSED expiration, the remaining amount becomes legally uncollectible.

The PPIA strategy is governed by IRM 5.14.2. It is not a settlement; the taxpayer does not negotiate a reduced lump sum as in an OIC. Instead, the taxpayer pays what they can afford each month, and if the CSED arrives before the balance is retired, the uncollected remainder expires by operation of law.

How to Qualify for a PPIA

The IRS determines the monthly payment amount for a PPIA through the same Collection Financial Standards framework used for OIC and CNC analysis. Income, allowable expenses under National and Local Standards, and net monthly disposable income are computed from a completed Form 433-A or 433-B. The resulting monthly payment figure is the PPIA payment. Specific CFS amounts must be verified at IRS.gov/businesses/small-businesses-self-employed/collection-financial-standards; this guide does not quote CFS dollar amounts as those figures change annually.

The IRS generally requires that the CSED have sufficient time remaining for a PPIA to be viable. The IRS will typically not approve a PPIA when the CSED is projected to expire in less than approximately 24 months, because there is insufficient time remaining for the payment structure to be meaningful. Verify current IRS PPIA viability thresholds under IRM 5.14.2 at IRS.gov, as these benchmarks are subject to update.

Ongoing Compliance Requirements

A taxpayer in a PPIA must remain in full compliance throughout the agreement term: all required returns must be filed on time, and estimated tax payments (if applicable) must be made. Failure to file or pay current taxes is grounds for the IRS to default the PPIA and resume collection action. The IRS also conducts annual reviews of PPIA financials. If the taxpayer's income increases or allowable expenses decrease, the IRS may require a higher monthly payment. Practitioners should advise clients to report material income changes proactively rather than wait for the IRS's annual review.

PPIA vs. OIC: The CSED Trade-off

The most important strategic comparison between PPIA and OIC centers on CSED treatment. A PPIA leaves the CSED clock running, which benefits the taxpayer if the balance is not retired before expiration. An OIC tolls the CSED during the consideration period (plus 30 days after rejection under IRC 7122(e)), which extends the IRS's collection window for the duration of the OIC review.

When the CSED has several years remaining and the taxpayer has a strong OIC case (Reasonable Collection Potential well below the liability), an OIC may produce a better outcome because it eliminates the liability entirely upon acceptance. When the CSED is shorter and the taxpayer's monthly disposable income is genuinely limited, a PPIA may be preferable because it lets the clock run without the toll that an OIC submission would impose.

Model both paths before recommending either. Compute: (1) the OIC settlement value under the applicable RCP formula, including the toll added to the CSED during OIC consideration; (2) the PPIA monthly payment and projected remaining balance at the adjusted CSED expiration date. The path that produces the better outcome for the specific client depends on their financial profile and remaining CSED window. See the OIC Reasonable Collection Potential financial analysis guide for the RCP calculation framework.

Section 7: CSED Expiration -- What Happens and What to Do

When the CSED for a specific assessment expires, the IRS's legal authority to collect that assessment terminates. The IRS cannot issue a levy against the taxpayer's property, cannot file suit to collect, and cannot take any enforcement action with respect to that assessment. Collection authority is extinguished by operation of law on the expiration date.

The Liability in the IRS System

CSED expiration does not legally eliminate the underlying tax debt from the IRS's books. The balance may remain reflected in the IRS system, and the IRS may continue to send balance-due notices in error. Practitioners should request a transcript after expiration to confirm the assessment is reflected as expired, and should respond to any post-expiration collection notices in writing, citing the CSED expiration date and the specific assessments covered. The IRS Internal Revenue Manual governs how expired assessments are to be handled by field personnel.

Federal Tax Lien Release After CSED Expiration

Under IRC 6325(a)(1), the IRS is required to release any Notice of Federal Tax Lien within 30 days after the CSED expires for the assessments covered by the lien. The lien is extinguished along with the collection authority. In practice, lien releases after CSED expiration do not always occur automatically within the 30-day window. Practitioners should monitor CSED expiration dates and, if the lien is not released within 30 days, formally request lien release in writing, citing IRC 6325(a)(1) and the expired CSED date. A lien that remains filed after CSED expiration continues to affect the taxpayer's credit and property transactions even though the underlying collection authority has terminated. For the full range of lien-relief options before CSED expiration, including discharge and subordination, see our Federal Tax Lien practitioner guide.

Post-Expiration Transcript and Documentation

After the CSED expires for an assessment, practitioners should obtain and retain: (1) the Account Transcript showing the expired assessment and its assessment date; (2) documentation of the CSED computation, including all TC 520 and TC 550 tolling entries and the resulting adjusted CSED; and (3) a copy of any lien release obtained from the IRS. This documentation serves as the record if the IRS mistakenly pursues collection after expiration.

Section 8: Form 900 (Tax Collection Waiver) -- Advising Clients

Form 900 is a Tax Collection Waiver through which a taxpayer voluntarily agrees to extend the CSED for a specified period. The IRS may request Form 900 during an examination, in connection with a collection alternative review, or in the context of extending installment agreement terms. Understanding what Form 900 does and what the IRS can and cannot require is essential before advising any client to sign.

What Form 900 Does

Signing Form 900 extends the CSED to the date specified in the waiver. The extension is irrevocable for the period stated: the taxpayer cannot later withdraw consent and restore the original CSED. Once Form 900 is executed, the extended CSED is binding regardless of whether the circumstances that led to the IRS's request have changed.

The IRS Cannot Compel Signature

The IRS cannot require a taxpayer to sign Form 900 as a condition of processing a collection alternative, entering an installment agreement, or granting a collection accommodation. The IRM acknowledges that the waiver is voluntary. If a Revenue Officer or ACS representative suggests that signing Form 900 is required or that refusal will result in adverse action, the practitioner should request the relevant IRM authority for that position. In most circumstances, no such authority exists.

Practitioner Protocol Before Any Client Signs Form 900

Before advising a client on whether to sign Form 900, practitioners must:

• Compute the current CSED for each assessment at issue, using the Account Transcript and accounting for all tolling events to date.
• Evaluate whether the extended CSED proposed in Form 900 provides any benefit to the client. In virtually all circumstances, it does not: the extension gives the IRS more time to collect and provides the client nothing in return.
• Determine whether there is any collection alternative the client is pursuing that genuinely requires the extension; and if so, whether the alternative's value outweighs the cost of extending the IRS's collection window.
• Document the analysis in the client file. If the client declines to sign Form 900 after being advised of the implications, document that decision as well.

The general practitioner guidance is direct: advise clients not to sign Form 900 unless there is a specific, articulable reason why the CSED extension benefits them. That reason exists in rare circumstances; in most collection representations, there is no benefit to the client, and the extension should be declined.

Frequently Asked Questions

Related Practitioner Guides

The following guides cover resolution tools and IRS procedures that intersect directly with CSED strategy and collection case management.

• IRC 6503: Statute of Limitations Tolling and CSED Suspension -- the statutory framework for all IRC 6503 subsections covering the assessment and collection clocks.
• Currently Not Collectible (CNC) Status: IRM 5.16.1 Practitioner Workflow Guide -- covers hardship standards, ACS vs. Revenue Officer paths, re-activation triggers, and the CSED strategy that makes CNC a preferred path when the collection clock is running short.
• IRS Collection Due Process (CDP) Hearing Practitioner Guide -- covers CDP hearing rights under IRC 6330, equivalent hearing procedures, Notice of Determination timelines, and Tax Court petition rights, including analysis of CDP tolling impact on the CSED.
• IRS Offer in Compromise Practitioner Guide -- covers OIC submission requirements, doubt as to collectibility vs. doubt as to liability, filing compliance requirements, and the OIC consideration process, including CSED tolling during review.
• Offer in Compromise RCP Financial Analysis: Practitioner Calculation Guide -- covers the Reasonable Collection Potential calculation, net realizable equity analysis, monthly disposable income computation, and OIC vs. PPIA vs. CNC decision modeling.
• IRS Federal Tax Lien Guide for Tax Practitioners -- covers NFTL filing, lien priority, discharge, subordination, withdrawal, and the interaction between CSED expiration and mandatory lien release under IRC 6325(a)(1).
• IRS Installment Agreement Practitioner Guide -- covers streamlined, standard, and partial pay installment agreement types, IRS financial analysis requirements, default triggers, and the PPIA qualification process under IRM 5.14.2.

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