ifso

ifso is a financial scenario simulator that models the big money decisions people keep putting off, then reports in plain English how each one plays out. Buying a house, retiring at 55, taking a job that pays less but starts sooner, all of them run year by year through an engine that carries real tax, mortgage, and market math instead of a flat growth assumption. The output isn't a wall of numbers. It's a sentence saying whether the money lasts and until what age, with the chart underneath for anyone who wants to see the shape of it rather than just the verdict. Every scenario is a full plan rather than a single calculation, so a house purchase drags along its mortgage, its property tax, and its effect on everything that comes after it.

The workflow is short enough to finish in one sitting. You enter the basics, age, income, savings, and what you own, then drop life events onto a timeline where they happen. The engine walks forward a year at a time and applies the rules that usually get skipped in a homemade spreadsheet, federal brackets, payroll tax, capital gains, state tax, and filing status. Mortgages amortize properly with property tax and insurance attached. Account types cover savings, brokerage, 401(k), IRA, home equity, and loans, so the model can tell a taxable account apart from a tax-deferred one instead of treating every dollar the same. Household income is modeled rather than assumed, so a two-earner plan behaves differently from a single-earner one at the same total, which is exactly where filing status starts to matter.

There's no bank linking anywhere in it. Everything is typed in by hand and the product never touches a financial account, which removes the usual objection to trying a planning tool at all. You can open the browser version and run a full model with no account, no email address, and no card. Signing up only matters if you want a plan saved for later. That's a rare ordering for anything in personal finance, and it says a fair amount about how the product expects to be judged, on the math rather than on the onboarding funnel.

Comparison is where it earns its keep. A plan can be duplicated, one assumption changed, and both versions put on the same chart, so the question stops being whether a plan works and becomes which plan works better. The paid tier adds Monte Carlo analysis that runs a plan against a thousand market histories and reports a probability of success rather than a single tidy line. That's the more honest version of the answer, since one deterministic projection always looks more certain than the future actually is, and a success rate is easier to act on than a curve. Comparison mode is the part that changes how the tool gets used, because most real decisions aren't yes or no questions. They're choices between two futures that both look survivable when you only look at one of them.

It's aimed at people standing at a fork who don't want to hire an advisor for one question and don't want to maintain a spreadsheet that breaks the moment a real tax rule enters it. Anyone who has built a retirement model in a spreadsheet knows the failure mode, where the compounding is right, the tax handling is a rough percentage, and the whole thing quietly overstates the result by years. The pitch here is that the math most people fudge is exactly the math that's built in, which is why the answers come out lower and more useful. There's a second audience too, people who already have an advisor and want to sanity check a recommendation before agreeing to it, which is far cheaper to do with a model than with a second opinion.

The free tier isn't a stripped demo. It includes the full engine with real tax handling, Social Security, houses, cars, and household income, plus one saved plan and the plain English answer. Pro costs $69 a year, roughly nine dollars a month, and adds unlimited plans, side-by-side comparison mode, Monte Carlo, and priority access to new features. A founding member rate of $59 a year is capped at the first hundred subscribers and stays locked in for as long as the subscription runs. Subscriptions cancel anytime, and data can be exported or deleted whenever the user wants. There's no trial clock to keep track of either, since the free tier just stays free and the upgrade is about volume and analysis rather than unlocking basic function.

Two things are worth knowing before committing. The tax engine is built for the United States, so brackets, filing status, and Social Security assumptions won't map cleanly onto other countries. The company is also clear that what it sells is modeling and not financial, tax, or investment advice, and that projections are estimates rather than promises. Used the way it's framed, as a way to pressure test a decision before making it, that boundary is reasonable, and stating it plainly on the site is a better sign than the alternative. Users outside the United States can still learn something from the mechanics, but the dollar answers won't be theirs.