Retirement Planner Feature Coverage Checklist

Retirement math is arithmetic plus a long list of edge cases. The list is what separates a shipped calculator from a defensible one.

A retirement planner’s core arithmetic is a few equations. Its coverage of the edge cases that arise in real retirement planning is where products differ. This checklist enumerates the edge cases and features a retirement planner might handle; it is intentionally longer than what any single tool addresses, because the point is to surface which items a caller’s current tool handles, which it does not, and which the caller’s audience actually needs. Not every audience needs every item. Every audience needs some subset, and the list is how a team identifies which.

Accumulation-phase features

• ✓Salary growth over time, not a constant salary assumption.
• ✓Contribution limits by account type (IRA, 401(k), HSA), read from a maintained source.
• ✓Age-based catch-up contributions above 50.
• ✓Additional catch-up bands where they exist under current law.
• ✓Employer match, including vesting schedules and per-pay-period versus true-up mechanics.
• ✓Roth versus traditional contribution mix.
• ✓Backdoor Roth pro-rata treatment across all pre-tax IRAs.
• ✓Mega-backdoor Roth capacity in plans that permit after-tax contributions.
• ✓HSA contributions treated as an accumulation vehicle, not only as a medical account.
• ✓Taxable-account contributions and their treatment for opportunity cost.

Projection-phase features

• ✓Real return versus nominal return, with the assumption named on the output.
• ✓Sequence-of-returns risk, or an explicit disclosure that the projection uses geometric averaging.
• ✓Stochastic simulation as an optional layer, not embedded in the base projection.
• ✓Multiple scenarios (best, base, worst) rather than a single point estimate.
• ✓Sensitivity to withdrawal rate as a range, not a single value.
• ✓Sensitivity to expected return as a range, not a single value.
• ✓Sensitivity to inflation as a range, not a single value.
• ✓A visible horizon (retirement age, life expectancy) that the user can adjust.

Drawdown-phase features

• ✓Required Minimum Distribution cohort ages, with the birth-year dependency handled correctly (SECURE 2.0 cohort ages).
• ✓RMD calculation on the applicable balance, not a rough approximation.
• ✓Roth account exemption from RMDs for the original owner.
• ✓Withdrawal-order strategies: taxable first, tax-deferred first, Roth last, or a caller-specified order.
• ✓Tax-bracket-aware withdrawal planning within a year.
• ✓Roth conversion planning, treated as its own model composed with the projection.
• ✓Social Security claiming age integration, respecting that the timing is a separate decision.
• ✓Medicare start-age transitions and their effect on health-cost inflation.
• ✓State income tax treatment of retirement withdrawals, or an explicit disclosure that state tax is excluded.

Cross-cutting features

• ✓Spouse or partner modeling as a first-class input, not an afterthought.
• ✓Named account types with their own tax treatment, not a single generic balance.
• ✓Long-term-care projection as an additive expense in retirement.
• ✓Legacy planning: what remains for heirs under different assumptions.
• ✓Ability to save and reload a scenario, with the assumptions preserved.
• ✓Ability to share a scenario with an advisor or family member.
• ✓Ability to export a scenario as a document a compliance reviewer or planner can read.

How to use the checklist

The checklist is not scored. It is used as a coverage inventory. Walk each item against the current tool and mark handled, partially handled, or not handled. The output is a specific list of gaps. Callers who then map the gaps against their audience’s needs — which subset of the list is most relevant for the users the tool serves — produce a prioritized list of what to add next. Not every gap is worth closing; the point is to close the ones that matter.

Legislative changes as a coverage item

Retirement law changes. The Windfall Elimination Provision and Government Pension Offset were both repealed by the Social Security Fairness Act on January 5, 2025, retroactive to January 2024.^[1] Retirement planners that referenced either as live rules during that period had to remove them; retirement planners that will be built next year should not include them as features at all. The coverage checklist should be revisited when law changes, not only when tools change; the two are on different schedules and both matter.

The features the checklist does not include

The checklist does not enumerate every possible retirement-planning feature. Estate planning across generations, trust structures, business-succession planning, and other adjacent topics are legitimate concerns and belong in adjacent tools. A retirement planner that tries to cover all of them typically covers none of them well. The checklist is scoped to the retirement-planning surface itself, and adjacent tools should have their own coverage checklists.

“The features are the checklist. Which features matter is the audience. Both questions are worth answering, in that order.”

Portfolio-level coverage

A team maintaining several retirement-adjacent tools — a general planner, a specific Roth conversion tool, a Social Security timing tool — can walk the checklist as a portfolio. Features that belong in specific tools versus features that belong in the general planner become clear at the portfolio level. A checklist item that could reasonably live in multiple tools is a portfolio-architecture question the team should answer once rather than case by case.

Three areas that most need explicit exclusion

Sequence-of-returns risk is the first. A retirement planner that uses a mean annual return without disclosing that sequence risk is not modeled is producing a projection that understates the probability of early failure. Either model it stochastically, or state the geometric-averaging assumption on the output. Silent omission is the failure mode; explicit exclusion is the honest posture.

State tax is the second. A national planner that treats federal tax as the total tax picture is misleading for users in high-tax states and overstating for users in no-tax states. Either model state tax as a caller-supplied input, or exclude it explicitly on the output. As with sequence risk, the exclusion is defensible; the omission is not.

Healthcare cost is the third. Pre-Medicare healthcare is a material variable expense in early retirement, and healthcare-cost inflation runs at a different rate than headline inflation. A planner that folds healthcare into a single expenses line item without letting the user see the sensitivity is doing the user a disservice. Either model healthcare separately, or disclose the omission on the projection.

How the checklist ages

The checklist itself is stable; the specifics change. Cohort ages for RMD move under law changes. Contribution limits move on the annual inflation cadence. Repeals happen, as WEP and GPO showed. A team that treats the checklist as a durable artifact and revisits it after any law change or catalog change keeps the checklist useful indefinitely. A team that walks it once at launch and never again finds that the checklist ages faster than the tool it audits, which is the opposite of what a checklist is for.

The gap between the checklist and the tool

The point of the checklist is to make the gap between what a calculator does and what a defensible retirement planner would do specific and visible. Teams that see the gap are equipped to close it in whatever order matches their audience and their engineering capacity. Teams that do not see the gap ship the same calculator for years while users go elsewhere for the features the calculator omits, without the team knowing which specific features drove the users away. The gap is the artifact; closing it is a series of decisions the team is now equipped to make.

The composition question the checklist raises

Several checklist items are legitimate features for either a single planner or a set of composed tools. Roth conversion planning can live inside a general retirement planner or as a separate tool; Social Security claiming timing can live inside a projection or as a separate model; long-term-care coverage can be integrated or standalone. The checklist does not answer where each feature should live; it surfaces the question. Teams that answer the composition question deliberately end up with a portfolio that is stronger than the sum of its features, because each tool knows what it is for and does that thing well.

The subset that most audiences actually need

A general-audience retirement planner does not need every item on the checklist. The subset that most audiences actually need is smaller than the full list and larger than what most shipped tools cover. The typical shipping tool covers half of accumulation, most of projection, and very little of drawdown; the typical user need covers most of accumulation, half of projection, and the specific drawdown features that map to that user’s stage. The gap is roughly the drawdown section. Teams that recognize this gap and close the drawdown items produce tools that stand out against most of the shipping alternatives, without needing to cover every accumulation edge case a specialist tool would.