AdviceOnly Calculators for AI assistants

How it works

When your question calls for a calculation, the assistant sends the numbers it has to our calculator, which runs the same math as the calculator on this site and sends back the result. Any number your question leaves out takes the calculator’s starting value, and the answer lists every value it used, so you can see what to correct.

If the assistant shows the calculator, changes you make there are worked out on your own device, and the assistant is told the new result so it can discuss it. Each answer also has a link that opens the same calculation on adviceonly.com.

Comparing several choices, such as two retirement ages, takes one run of the calculator for each. If the assistant is unsure which calculator fits, it can ask, and if none does, it is told that AdviceOnly has no calculator for that question yet.

Add it to your assistant

Add the app by its address: https://mcp.adviceonly.com/mcp. No account or sign-in is needed. Menu names differ between plans and change over time, so look for the nearest match.

• Claude: open Customize, then Connectors, and add a custom connector. Paste the address and choose no sign-in. In a conversation, turn it on from the connectors menu.
• ChatGPT: open Plugins and add a custom MCP server. Paste the address and set authentication to none. In a new conversation, add it from the tools menu.
• Other assistants that support MCP apps: add a remote MCP server with the same address. An assistant that supports tools but not apps gives you the written answer and the link, without the calculator on screen.

What you can ask

Questions like “I pay my advisor 1% on $800,000. What does that cost over 20 years next to a flat fee?”, “How much tax would converting $40,000 to a Roth add this year?” or “What’s my RMD on a $500,000 IRA at 75?” Every calculator on this site is available:

• Financial Advisor Fee Calculator : What a financial advisor costs over time under a percentage-of-assets, flat, hourly or project fee, side by side, with the break-even percentage against each.
• RMD Calculator : Your required minimum distribution for the year from IRAs, 403(b)s and a 401(k), which account it must come from and by when, with the spouse table, QCDs, the still-working rule and a projection to age 95.
• Social Security Tax Calculator : How much of your Social Security is taxable, with the IRS worksheet, the federal income tax it adds, and what the next $1,000 of IRA income, municipal interest or capital gains would cost.
• Coast FIRE Calculator : Your Coast FIRE number: what you need invested today to stop saving for retirement and still retire on time, the age you catch up with it if you keep saving, and what your savings would pay for now, with optional Social Security.
• Inherited IRA RMD Calculator : The least you must withdraw from an inherited IRA this year and when it must be empty, under the 10-year and life-expectancy rules, with withdrawal plans compared at your federal tax bracket.
• Retirement Calculator : How much you need saved to retire after income tax, from pretax, Roth and taxable accounts, single or married, with Social Security, a pension and required minimum distributions; the yearly saving that gets you there; five withdrawal orders and eight spending rules compared; and how often your plan lasts across 1,000 simulated markets.
• No Tax on Overtime Calculator : What the 2025–2028 overtime deduction is worth to you: the part of your overtime that counts, the cap and phase-out, and your federal income tax with and without it, including the refundable child tax credit.
• No Tax on Tips Calculator : What the 2025–2028 tips deduction is worth to you: the $25,000 cap and phase-out, the limit for tips in your own business, and your federal income tax with and without it, including the refundable child tax credit.
• Car Loan Interest Deduction Calculator : Whether your car loan qualifies for the 2025–2028 car loan interest deduction, the interest you pay this year estimated from your loan, and what the deduction is worth after the $10,000 cap, the phase-out and the refundable child tax credit.
• Itemized vs Standard Deduction Calculator : Whether to itemize or take the standard deduction for 2025 or 2026, what the better choice saves in federal income tax under the new limits on state and local taxes and charitable gifts, and whether bunching gifts would save more.
• IRMAA Calculator : Your Medicare IRMAA surcharge for Part B and Part D from the income on your return two years earlier, for one person or a couple, with the full bracket table, how far you are from the next bracket, and your whole premium with any late-enrollment penalties.
• Roth Conversion Calculator : The federal tax a Roth conversion adds on your 2025 or 2026 return, counting Social Security, the senior deduction, the Marketplace premium tax credit and IRMAA two years later, how much more you could convert before each step, the future tax rate at which converting comes out ahead, and a year-by-year plan until RMDs start.
• Mortgage Payoff Calculator : How much sooner your mortgage is paid off and how much interest you save with extra payments, what a recast does, when PMI ends, and whether investing the money instead would leave you ahead.
• Debt Payoff Calculator : When your credit cards and loans are paid off, and the interest you pay, highest rate first, smallest balance first or with the extra split evenly; what paying only the minimums costs; and whether a consolidation loan or balance transfer saves money.
• Home Affordability Calculator : How much house you can afford: the price that fits the housing budget you set, with upkeep counted, beside what a lender could approve under Fannie Mae, FHA or VA limits and the most they allow, tested against your savings, rising costs and an adjustable rate.
• Estimated Tax Calculator : How much federal estimated tax to pay each quarter for 2025 or 2026, and the smallest amount that avoids the underpayment penalty, from self-employment profit, wages and other income, with self-employment tax, catch-up payments and the penalty if you pay nothing.
• Bonus Tax Calculator : What a bonus or RSU vest leaves you after the flat 22% (37% over $1 million) or aggregate withholding, Social Security and Medicare, and what it really adds to your 2025 or 2026 tax, so you see what you will owe or get back when you file.
• Capital Gains Tax Calculator : The federal tax a sale of stocks, funds, crypto or collectibles adds to your 2025 or 2026 return, with the gain stacked on your other income, netting against other gains, losses and carryovers, the 3.8% tax, inherited and gifted basis, and the long-term gain you could still take at 0%.
• Tax Bracket Calculator : Your 2025 or 2026 federal tax bracket, your average tax rate, and what your next dollar of wages, business profit, retirement income, interest or gains really costs, counting Social Security and Medicare, the child and earned income credits, Social Security taxation and the 0% gains rate.
• 401(k) Withdrawal Calculator : What a 401(k) withdrawal before 59½ costs in federal tax and the 10% additional tax, what is withheld and owed at filing, and whether a 401(k) loan is cheaper.
• Health Plan Comparison Calculator : Which way of covering you, your spouse and your children with employer health plans costs least: an HSA-eligible plan or a PPO or HMO, one employer’s plans or both, after premiums, care, HSA money and the tax they save, this year, in a bad year and by 65.
• 401(k) Match Calculator : What percent of each paycheck gets your whole employer 401(k) match, whether reaching the yearly limit early loses some, and the rate that reaches the limit and keeps it all, with catch-ups, a job started this year and student loan matching.
• Compound Interest Calculator : How much a starting amount and monthly or yearly additions grow at any compounding frequency, how much of it is growth, what it is worth in today’s dollars, and what starting your additions a few years later would cost.
• Refinance Calculator : Whether refinancing your mortgage, or paying points for a lower rate, costs less than keeping your loan over the years you keep the new one, counting closing costs, mortgage insurance and what you’d still owe, with the month it pulls ahead and the month a longer term falls behind.
• Home Equity Loan Calculator : What borrowing against your home costs with a home equity loan, a HELOC or a cash-out refinance over the years you’d carry the debt, with the line’s payment when repayment starts and how much each lets you borrow.

What it does not do

• It follows federal rules. State income tax is left out, except where a calculator lets you enter a flat state rate, and each answer states the tax year it used.
• It knows only the numbers it is given. A calculation is not a recommendation for your situation and is not investment, tax or legal advice.
• It does not connect to any account, read your conversation, or remember anything between questions.

What is sent, and what we keep

AdviceOnly does not store financial inputs entered into our calculators. The assistant sends our calculator only the numbers a calculation needs (and, when it asks which calculator fits, your question as it words it); the calculator uses them to work out the answer and keeps none of them. We count how often each calculator is used, from which assistant, and when a request fails, without any of the numbers or text that were sent. Your conversation itself stays with the company that runs the assistant, under its own policy. Details are in our privacy policy.

Who makes it

Advice Only, PBC (colloquially “AdviceOnly”) is an SEC-registered investment adviser and a Delaware Public Benefit Corporation (CRD# 334039, SEC File No. 801-135290). We do not manage investment portfolios, sell financial products, or hold custody of client assets. Our Form ADV and Form CRS are on the disclosures page.

Each calculator is tested with multiple methods across thousands of scenarios and reviewed by an experienced CFP® professional; how we test our calculators explains both. Each keeps a dated version history on its page, and new figures are added when the IRS, CMS or SSA publish them. Use of the app is covered by our terms of service.

If something goes wrong