Automated Collection System (ACS)
The IRS collection operation that issues the LT-series letters. It is a call-centre-and-notice function rather than an assigned officer.
Full Definition
The Automated Collection System is the IRS collection function that works balances by notice and telephone rather than by assigning a revenue officer to visit.
You can recognise its output. The LT-series letters on this site — LT11, LT14, LT16, LT18, LT19, LT26, LT27, LT33, LT38, LT39, LT40, LT73, LT75 — are issued from it, and they share a shape: a toll-free number rather than a named contact, an instruction to follow what is printed on the notice, and self-service routes to payment.
The practical consequence is that there is usually no one person handling the account. The number on the notice reaches the function, not an individual, which is why every one of those letters tells you to work from what is printed on the paper.
This page does not describe how ACS decides what to issue, or the point at which an account leaves it for field collection, because no retrieved IRS source states either.
What to do next
Whatever the LT letter says to do, do it from the notice — the number reaches a function rather than a person, and the dates and instructions printed on your copy are the ones that govern.
What this page does not say
- No taxpayer-facing IRS page describing the Automated Collection System as a function was located at any URL tried. This entry describes what the LT-series notices have in common, which is observable from the notices themselves, and does not describe ACS procedure, thresholds, or the transfer of accounts to field collection.
Sources
- Understanding your LT40 notice — Internal Revenue Service, retrieved 2026-08-21
- Publication 594, The IRS Collection Process — Internal Revenue Service, retrieved 2026-08-18
Last reviewed 2026-08-21 by Tax Resolution Clarity editorial.
Sourced to primary IRS materials and editorially reviewed. Not reviewed by a tax professional. Not tax advice.
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Where to go next
The IRS publishes the rules this page describes. Your own notice governs your dates.