Full app product guide · Reviewed September 14, 2026

A free after-tax portfolio manager for your income questions.

Editorial attribution: AfterTaxUS product documentation. This page documents the app’s workflow and limitations, not a professional review or a promise of investment results.

AfterTaxUS brings multiple accounts and income sources into one workbook for after-tax income estimates before and after a change. Use it to inspect tax assumptions, test replacement-investment what-ifs and revisit saved scenarios. It is an educational planning app, not a brokerage, trade-execution service, tax-return preparer or investment adviser.

AfterTaxUS charges no fees for the full app. A free account is required to save and return to a workbook. Optional external AI plans, connector availability and charges vary by provider; free AfterTaxUS access does not include a paid assistant subscription.

Start with accounts, then classify each income source

The workbook separates accounts, assets, investment rows and tax settings. An account supplies its tax status and income-display choices. An asset supplies a yield assumption and tax treatment. An investment row ties the amount and income assumptions to the selected account and asset. Check those relationships before interpreting a total.

Multiple accounts and income rows let you examine investments alongside sources such as wages, Social Security, pensions and rental income. Keep income types distinct: background wages are not interchangeable with dividends, and money moving between accounts is not automatically new income. Use consistent units and do not count the same income twice.

Taxable accounts, tax-deferred accounts and tax-free accounts need different assumptions. For example, traditional IRA earnings generally are not taxed until distributed; qualified Roth IRA distributions generally are tax-free, but qualification matters. An account name cannot establish withdrawal eligibility. See IRS Topic 451: Individual retirement arrangements.

Review the asset’s tax treatment independently of its name. Qualified dividends are a subset of ordinary dividends reported on Form 1099-DIV; avoid duplicating the qualified amount as additional income. See IRS Publication 550: Investment Income and Expenses. The app’s catalog yields are illustrative samples, not live quotes or recommendations.

Keep tax liability separate from spendable income

An income total can be misleading if some cash stays invested or is otherwise unavailable to spend. The full app has separate controls for inclusion, display exclusion and scenario changes:

• Include checkbox: determines whether a row contributes to calculations. Leave genuine income included when you need it represented in the tax model.
• Account exclusion from after-tax income: removes that account’s included income from the spendable-income display, but included rows still contribute to the tax calculation according to their tax treatment. This is not a tax exemption.
• WhatIf checkbox: enables the row’s replacement scenario. It is independent of inclusion and of a visual row highlight.

For example, a taxable account whose income stays invested may still contribute to the tax estimate while its cash is excluded from the spending total. Unchecking its income rows would ask a different question by removing them from the calculation. Review excluded-income information alongside the tax breakdown rather than expecting every income dollar to appear as spendable cash.

Compare a change without losing your starting point

A baseline is the reference for displayed differences. A saved version preserves a workbook scenario you can return to. They serve different purposes: setting a comparison reference is not a substitute for keeping a named version of the assumptions you want to retain.

1. Establish the starting case. Sign in, enter accounts and income, verify tax treatments, and resolve warnings. Check the filing status, deductions and applicable state/local settings.
2. Set a baseline and save a named version. Choose a name that explains the starting assumptions so you can distinguish it from later experiments.
3. Try a specific replacement. Open WhatIf, choose the replacement asset for the row, and confirm that its WhatIf checkbox is active. Use alternatives you want to examine; the app does not decide what you should buy.
4. Inspect the difference. Compare before-tax and after-tax income, baseline deltas and tax breakdowns. A larger distribution can come with a larger tax cost. A result is conditional on the complete workbook, not just the edited row.
5. Keep or reverse the experiment. Save a separate named version if you want to revisit it, use undo/redo for edits, or restore your saved starting version. Recheck the active rows and baseline after restoring.

Changing one assumption at a time makes the result easier to explain. Before comparing saved cases, confirm that their income units, deduction choices, account exclusions and tax settings are intentionally the same or intentionally different. A baseline delta is not a realized return, and a what-if does not place an investment order.

What federal, state, local and W-2 settings cover

• Federal: the current 2025 model uses income classifications, filing status and deduction assumptions to estimate tax. Review the breakdown and warnings. Do not assume complete treatment of every credit, AMT situation, retirement distribution rule or deduction.
• State: state selection and settings affect the estimate, but do not mean every state rule, exemption, surcharge, deduction or credit is modeled or independently validated. Residency and multi-state situations may require outside calculations.
• Local: the app offers a supported local-tax catalog and a custom/manual local-tax setting. Coverage is not every city, county or district. Verify the selected locality, relevant income categories and applicable assumptions; an available rate is not proof it applies to you.
• W-2 payroll: supported payroll settings extend the income estimate for wage scenarios. Correctly classify wage income and review the payroll breakdown. These controls do not make the app a paycheck withholding calculator or an employer payroll service.

Income types also interact. Dividends and tax-exempt interest can affect the taxable portion of Social Security benefits; use IRS Publication 915 to check the federal benefits rules. Our living off dividends guide separates hypothetical monthly-income arithmetic from tax-model results.

After-tax income alone does not measure investment risk, fees, liquidity, future price changes or total return. The app does not establish suitability, sustainable withdrawals or future returns. Consult current official guidance and a qualified professional for consequential decisions. IRS references explain concepts; they do not imply endorsement or validation of AfterTaxUS.

Optional MCP access lets an authorized assistant work with your model

The full app supports an optional Model Context Protocol (MCP) connection for compatible assistant clients, including compatible ChatGPT or Claude configurations. This is more than discussing a screenshot: exposed tools can read workbook data, update individual investment rows or batches, control what-ifs, highlight rows and request portfolio tax calculations.

You must authorize access. The client must support the connection and expose the actions you need. A public product page does not give an assistant private workbook access or permission to change it. Client features, plans and authorization controls vary; do not assume every client supports every action.

1. Save a named version before connecting. Obtain connection details through the signed-in app and add them only in a trusted client’s connector setup. Treat the private connector URL as a secret because it grants workbook access; do not publish it or include it in shared screenshots.
2. Start with a request to read and identify the exact rows, assumptions and warnings. Confirm that the client exposes the required tools before asking it to calculate or edit.
3. Specify the what-if you want compared. Ask for current and proposed results before authorizing changes. Ask the assistant to obtain approval before modifying or saving the workbook; that instruction is a workflow precaution, not a guarantee of client-side enforcement.
4. Review changes in the app. Check include and WhatIf checkboxes separately from row highlights. Use the available connection controls to revoke access when it is no longer needed.

AI interpretations can be wrong, and tool-generated estimates still depend on the inputs and model scope. Connecting does not authorize brokerage trades. AfterTaxUS is not affiliated with or endorsed by OpenAI or Anthropic. See AI tax tools and MCP access and the MCP workflow example.

Do you need the full app or a quicker calculator?

• Investment comparison calculator: compare two options using one shared amount without an account. It calculates in your browser using simplified background income and federal/state assumptions, excluding local and payroll taxes.
• Income calculator: get a broad estimate from ordinary and investment income, filing status, deductions, state and supported local settings without logging in. Calculations use AfterTaxUS backend services.
• Full portfolio app: use multiple accounts and income rows, replacement-investment what-ifs, comparison baselines, saved workbook versions and optional authorized MCP access. Calculations and saved workbooks use backend services.

All three AfterTaxUS tools are free. The full app’s account requirement is for saving and returning to your workbook, not a paid upgrade. Opening the full app from the investment comparison does not automatically transfer that calculator’s inputs.

What to know before entering personal information

No bank connection is needed for manual entry, and AI access is optional. Share only the information you intend AfterTaxUS and any connected assistant provider to receive. Read the privacy policy for saved-workbook, backend and usage-analytics information, and the terms for use of the service.

For the full methodology and exclusions, see how AfterTaxUS works. Start with a small, clearly labeled scenario and verify the classifications before building a larger model.