IRS Publication 1458 – Actuarial Valuations Version 4B – If you’re involved in estate planning, charitable giving, or valuing interests in trusts for tax purposes, IRS Publication 1458 is an essential resource. Titled Actuarial Valuations Version 4B – Unitrust Remainder Examples (For One Life, Two Lives, and Terms Certain), this official IRS guide helps taxpayers, attorneys, CPAs, and financial advisors accurately calculate the present value of remainder interests in charitable remainder unitrusts (CRUTs) and similar arrangements.
Revised in June 2023 (Rev. 6-2023, Catalog Number 10719U), Publication 1458 Version 4B incorporates updated actuarial tables based on the 2010CM mortality experience. It applies to income, estate, and gift tax valuations under IRC Section 7520 for most transfers on or after June 1, 2023.
This comprehensive guide explains everything you need to know about IRS Publication 1458, including its purpose, key tables, step-by-step examples, effective dates, and how to access the full resources.
What Is IRS Publication 1458?
IRS Publication 1458 provides actuarial tables and detailed computational examples specifically for valuing unitrust remainder interests. A unitrust (such as a CRUT under IRC Section 664) pays a fixed percentage of the trust’s annually revalued assets to one or more beneficiaries for life, a term of years, or a combination.
The publication focuses on the remainder interest (typically passing to charity), which is critical for:
- Claiming charitable deductions on income tax returns (Form 1040 Schedule A).
- Valuing taxable gifts or estate inclusions.
- Determining generation-skipping transfer tax implications.
Unlike Publication 1457 (for annuities, life estates, and remainders) or 1459 (for depreciable property adjustments), Version 4B is dedicated to unitrust-specific factors. It does not contain the full multi-thousand-row tables — those are available as free Excel downloads on the IRS website — but it delivers clear, practical examples showing exactly how to apply them.
Key Updates in Version 4B (June 2023)
Version 4B reflects the IRS’s periodic update to actuarial tables every decade to match current mortality data:
- Mortality basis: Switches to Table 2010CM (derived from the U.S. Decennial Life Tables for 2009–2011, Total Population).
- Effective date: Required for valuation dates on or after June 1, 2023.
- Transition rule: For valuations between May 1, 2019, and May 31, 2023, taxpayers could choose either the prior 2000CM tables or the new 2010CM tables — but consistency is mandatory across all interests in the same property on the same date.
These changes generally result in slightly different valuation factors due to improved longevity assumptions. Always verify the applicable Section 7520 rate (120% of the federal mid-term rate, rounded to the nearest 0.2%) for the month of the transfer (or one of the two prior months, at election).
Associated Actuarial Tables in Publication 1458 Version 4B
The publication references these core tables (full versions available as downloadable spreadsheets):
- Table U(1): Single-life unitrust remainder factors (adjusted payout rates 0.2%–20.0%).
- Table U(2): Two-life last-to-die unitrust remainder factors (split into five parts by payout rate range).
- Table D: Term-certain remainder factors.
- Table F: Payout rate adjustment factors (for non-annual or end-of-period payments).
- Table Z: Commutation factors (for hybrid life-and-term interests).
- Table 2010CM: Underlying mortality table (lₓ values to seven digits).
All tables support Section 7520 interest rates from 0.2% to 20.0% in 0.2% increments.
How to Use the Tables: Step-by-Step Examples from the Publication?
Publication 1458 walks through five practical examples (all assuming a 5.0% stated payout rate paid quarterly at the end of each quarter and a 3.2% Section 7520 rate). Here’s a summary:
Example A – Computing the Adjusted Payout Rate
When payments occur more frequently than annually, adjust the stated rate using Table F.
Formula: Adjusted Payout Rate = Stated Rate × Table F Factor.
Result in the example: 4.903%.
Example B – Single-Life Remainder Interest
Valuing a CRUT remainder after one person’s death.
Use Table U(1) and linear interpolation if the adjusted rate falls between tabulated values.
Example outcome: Remainder factor ≈ 0.32074 on a $1,500,000 transfer → $481,110 charitable deduction.
Example C – Two-Life Last-to-Die Remainder
For a unitrust continuing until the second spouse dies.
Apply Table U(2) with interpolation.
Example outcome: Factor ≈ 0.42308 on an $800,000 transfer → $338,464 remainder value.
Example D – Term-Certain Remainder
For a fixed-term unitrust (e.g., charitable lead unitrust).
Use Table D.
Example outcome: Factor ≈ 0.470492 on a $5,000,000 transfer → $2,352,460 remainder.
Example E – Life Plus Term of Years (Earlier of Death or Fixed Term)
Hybrid scenario using Table Z commutation factors.
Example outcome: Retained interest value calculated via interpolated payout factor.
Pro tip from the IRS: You may also compute factors directly with actuarial software or formulas, as long as you maintain at least as many significant digits as the tables (typically five decimal places) and remain consistent.
Historical Synopsis of Actuarial Tables
The publication includes this helpful timeline:
| Period | Mortality Table | Publications Used |
|---|---|---|
| 1951–1970 | US1938 | Pub 11 |
| 1971–1983 | LN | Pubs 723 series |
| 1983–1989 | CM | Pubs 723C–E |
| 1989–1999 | 80CNSMT | 1457/1458/1459 (1989) |
| 1999–2009 | 90CM | 1457/1458/1459 (1999) |
| 2009–May 2023 | 2000CM | 1457/1458/1459 (2009) |
| June 2023–present | 2010CM | 1457/1458/1459 (2023) |
Where to Download IRS Publication 1458 and Full Tables?
- Official PDF: https://www.irs.gov/pub/irs-pdf/p1458.pdf
- Full actuarial tables & spreadsheets: Visit the IRS Actuarial Tables hub at https://www.irs.gov/retirement-plans/actuarial-tables. Download Excel files for Table U(1) 2010CM, Table U(2), etc.
- Related publications: Pub 1457 (Version 4A – annuities/life estates) and Pub 1459 (Version 4C – depreciable property).
Common Applications in Tax Planning
- Charitable remainder unitrusts (CRUTs) for income tax deductions while retaining lifetime income.
- Charitable lead unitrusts (CLUTs) for estate/gift tax minimization.
- GRUTs (grantor retained unitrusts) under Chapter 14.
- Estate tax valuations for decedents dying after May 31, 2023.
Important reminder: Always consult a qualified tax professional or actuary. Special rules apply for short taxable years, certain payment sequences, or when the standard tables cannot be used (see Treas. Reg. § 1.7520-3).
Frequently Asked Questions (FAQs)
- Q: When must I use Version 4B tables?
A: For valuation dates on or after June 1, 2023. - Q: Can I still use the old 2000CM tables?
A: Only for pre-June 1, 2023 valuations (with the 2019–2023 transition option). - Q: Where do I find the Section 7520 rate?
A: IRS publishes monthly rates in the Internal Revenue Bulletin or on the actuarial tables page. - Q: Are the tables available in PDF or only Excel?
A: Full factors are in downloadable spreadsheets; the publication itself is PDF with examples.
Conclusion: Why IRS Publication 1458 Version 4B Matters
Accurate actuarial valuations directly impact charitable deductions, taxable gifts, and estate tax liabilities. IRS Publication 1458 Version 4B simplifies complex calculations with clear examples and points you to the latest 2010CM-based tables.
For the most current guidance, always start at IRS.gov. Download Publication 1458 today and pair it with the Excel tables for precise, regulation-compliant results.
Need help? Speak with your estate planning attorney or CPA to ensure your unitrust valuations comply with the latest IRS standards under Section 7520.
All information sourced directly from official IRS documents (Publication 1458 Rev. 6-2023 and the Actuarial Tables page, last updated August 2025). This article is for educational purposes only and is not tax or legal advice.