Statute Expiration Dates (ASED, CSED, RSED)

Statute dates govern when the IRS can assess taxes, when the IRS can collect liabilities, and when a taxpayer can claim refunds.

Comparison Table

Statute	Full Name	Standard Limitation Period	What It Controls	Easy Memory
ASED	Assessment Statute Expiration Date	3 Years from return due date or filed date (whichever is later)	Deadline for IRS to assess additional tax	A = Assess
CSED	Collection Statute Expiration Date	10 Years from date of assessment (plus tolling events)	Deadline for IRS to collect an assessed liability	C = Collect
RSED	Refund Statute Expiration Date	3 Years from filing date OR 2 Years from payment date (whichever is later)	Deadline for taxpayer to claim/request a refund	R = Refund

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1. ASED (Assessment Statute Expiration Date)

Core Question

"How long does the IRS have to assess additional tax?"

Key Rules

• Generally 3 years from the date the tax return was filed or the due date (usually April 15), whichever is later.
• Exceptions that extend or remove ASED:
  • No return filed (SFR / Substitute for Return): Statute never begins to run!
  • Fraudulent return: No statute of limitations.
  • Substantial omission of income (>25%): Extends to 6 years.
  • Consents / Form 872: Taxpayer agreements extending the assessment period.
• Relevant Transaction Codes:
  • TC 560: Statute-related transaction updating or maintaining Master File ASED.

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2. CSED (Collection Statute Expiration Date)

Core Question

"How long does the IRS have to collect this balance?"

Key Rules

• Generally 10 years from the date the tax liability was legally assessed (established by TC 150, TC 290, TC 300, etc.).
• Tolling / Suspension Events:
  • Filing for Bankruptcy (suspends CSED while in bankruptcy plus 6 months).
  • Submitting an Offer in Compromise (OIC) (suspends CSED while under consideration plus 30 days).
  • Requesting a Collection Due Process (CDP) hearing.
  • Entering into an Installment Agreement pending review.
  • Living outside the United States continuously for 6+ months.

CSED Calculation Caution

Because tolling events stop the clock, the actual expiration date often extends well past the original 10 calendar years. Always check Master File / IDRS CSED calculations.

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3. RSED (Refund Statute Expiration Date)

Core Question

"How long does the taxpayer have to claim a refund or credit?"

Key Rules

Internal Revenue Code (IRC) Section 6511 dictates:

1. 3-Year Lookback Rule: Within 3 years from the date the return was filed.
2. 2-Year Lookback Rule: Within 2 years from the date the tax was paid.
3. If no return was filed, only payments made within the last 2 years can be refunded.

Practical Example

If a taxpayer forgot to file their 2021 return which had excess withholding, they generally have until April 15, 2025 to file and claim their refund before the RSED expires and the money is barred by law.

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4. FRZ (Freeze Codes)

Core Question

"What is preventing or restricting normal account/module processing?"

• Freeze codes appear on account transcripts and screen displays (e.g., -V, -Z, -R, -L).
• A freeze stops or redirects:
  • Refund issuance
  • Offset to other tax periods
  • Notice issuance
  • Collection enforcement
• Always identify the freeze condition before explaining next steps to a caller!