# Definition of Last Known Address
> **IRS** · Final and temporary regulations. · Published 2001-01-12 · Effective 2001-01-12 · 66 FR 2817
## Document
- **Document number:** 01-623
- **Category:** other
- **Sub-agency:** IRS
- **Federal Register citation:** 66 FR 2817
- **CFR reference:** 26 CFR 1
- **Publication date:** 2001-01-12
- **Effective date:** 2001-01-12
- **Treasury docket:** TD 8939
## Abstract

This document contains final regulations defining last known address in relation to the mailing of notices of deficiency and other notices, statements, and documents sent to a taxpayer's last known address. The final regulations affect taxpayers who receive notices of deficiency and other notices, statements, and documents sent to taxpayers' last known addresses.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2001/01/12/01-623/definition-of-last-known-address)
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