401k
Research & Transparency

401(k) Sources & References

Explore the official government sources, retirement resources and research references used by 401k.blog to explain 401(k) contributions, taxes, investing, fees, withdrawals, retirement planning and related topics.

Our Editorial Policy Financial Disclaimer
401k.blog Source Library
IRS Taxes & contribution rules
DOL Fees & retirement plans
Investor.gov Investing education
SSA Social Security
Source Transparency

Where 401k.blog gets its retirement information

Retirement rules are not static. Contribution limits, tax provisions and other retirement-plan rules can change. We therefore prioritize authoritative sources and use official government information whenever it is available.

01

Primary sources first

For tax rules, contribution limits, Roth 401(k) rules and required minimum distributions, we prioritize information published by the Internal Revenue Service.

02

Plan-specific rules still matter

Federal rules do not describe every feature of every employer plan. Your Summary Plan Description and plan administrator can provide the rules that apply to your particular 401(k).

Official Resources

Primary government sources

These organizations form the core reference library for 401k.blog's retirement education content.

Research By Topic

Find sources for specific 401(k) topics

Our content clusters are supported by the source organizations most relevant to each retirement topic.

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Contribution Limits

Annual elective-deferral limits, annual additions, compensation limits and catch-up contributions.

Explore contribution limits →
R

Roth 401(k)

Designated Roth contributions, taxation and qualified distributions.

Explore Roth 401(k) →
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401(k) Fees

Investment fees, administrative expenses, service fees and participant disclosures.

Explore 401(k) fees →
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Investing

Investment options, diversification, target-date funds, index funds and investment expenses.

Explore 401(k) investing →
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Rollovers

401(k) rollover concepts, retirement-plan transfers and related tax considerations.

Explore 401(k) rollovers →
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RMDs

Required minimum distributions and applicable retirement plan distribution rules.

Explore RMD resources →
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Retirement Planning

Retirement savings, income planning and Social Security resources.

Explore retirement planning →
IRA

401(k) vs IRA

Retirement-account differences, contribution rules and tax treatment.

Compare 401(k) and IRA →
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Employer Plans

Employer matching, vesting, plan documents and participant responsibilities.

Explore employer matching →
Source Directory

401(k) source reference by topic

A quick reference for the primary organization we use when researching common retirement topics.

Topic Primary Source 401k.blog Resource
401(k) contribution limits Internal Revenue Service Contribution Limits →
Catch-up contributions Internal Revenue Service Catch-Up Contributions →
Roth 401(k) Internal Revenue Service Roth 401(k) →
Required minimum distributions Internal Revenue Service RMD Guide →
401(k) fees U.S. Department of Labor 401(k) Fees →
ERISA U.S. Department of Labor 401(k) vs IRA →
Investment education SEC Investor.gov 401(k) Investing →
Target-date funds SEC Investor.gov Target-Date Funds →
Social Security benefits Social Security Administration Retirement Planning →
Full retirement age Social Security Administration Retirement Planning →
Editorial Standards

How 401k.blog uses sources

Our source approach is designed to keep retirement information useful, transparent and appropriately qualified.

Our source principles

  • Government and primary sources are preferred for laws, regulations and annual limits.
  • Time-sensitive retirement figures are checked against current official information.
  • We distinguish official limits from estimates, projections and illustrative examples.
  • External sources are attributed when they provide factual information used in an article.
  • We avoid presenting educational calculator outputs as guaranteed future results.

Plan-specific information

  • Employer plans can have rules that differ from general federal limits.
  • Your Summary Plan Description is an important source for your individual plan.
  • Employer matching formulas can vary by plan.
  • Investment menus, fees and vesting schedules can also differ between plans.
  • When a question concerns your specific plan, verify the details with your plan administrator.
401(k) Research Hub

Explore the 401k.blog knowledge base

Use the source library alongside our calculators, guides and retirement-planning resources.

FUNDAMENTALS What Is a 401(k)? FUNDAMENTALS How Does a 401(k) Work? CONTRIBUTIONS 401(k) Contributions ANNUAL LIMITS 2026 401(k) Contribution Limits ANNUAL LIMITS 2027 401(k) Contribution Limits CALCULATORS 401(k) Calculator Hub INVESTING 401(k) Investment Options FEES 401(k) Fees Explained COMPARISON 401(k) vs IRA ROTH Roth 401(k) Guide ROLLOVERS 401(k) Rollover Guide PLANNING Retirement Planning
Frequently Asked Questions

401(k) sources and references FAQ

Common questions about the information and sources used throughout 401k.blog.

401k.blog primarily uses authoritative government and institutional sources. These include the Internal Revenue Service, U.S. Department of Labor, SEC Investor.gov and Social Security Administration, along with applicable plan documents and other authoritative references.
Yes. The IRS publishes the annual retirement-plan contribution limits and related cost-of-living adjustments. For example, the IRS lists the 2026 basic 401(k) elective deferral limit as $24,500 and the standard age-50 catch-up amount as $8,000.
Your plan's Summary Plan Description, plan documents and plan administrator are important sources for plan-specific information such as matching formulas, vesting provisions, investment choices and certain distribution rules.
No. The calculators on 401k.blog are educational tools designed to illustrate possible scenarios. They are not official government calculators and their results should not be interpreted as guarantees or individualized financial advice.
The Social Security Administration provides official retirement benefit calculators. Some SSA tools can use your earnings record through your personal my Social Security account.
Time-sensitive information such as annual contribution limits should be reviewed when new official guidance is published. Other retirement information should also be checked when laws, regulations or official guidance change.

Research your 401(k) with reliable sources.

Start with the official sources, then use 401k.blog's calculators and guides to understand the concepts in a simpler, practical format.

Explore 401(k) Calculators Start With 401(k) Basics
Educational & Source Disclaimer

401k.blog provides educational information about 401(k) plans, retirement accounts and retirement planning. Information on this website is not financial, tax, legal or investment advice. Official government sources should be consulted for current rules, and your plan documents or plan administrator should be consulted for plan-specific information.

External sources linked from this page are maintained by their respective organizations. 401k.blog does not control those websites or guarantee the completeness of their information.

401k.blog

 Clear guides, useful calculators and practical retirement resources to help you understand your 401(k), contributions, employer matching, Roth options, rollovers and long-term savings.

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