Estimate 2026 HSA contribution room for two spouses across HDHP changes, FSAs, employer contributions, age-55 catch-ups, the last-month rule, and Medicare Part A timing.
Illustrative married-household example loaded
Replace the sample coverage, FSA, contribution, and Medicare timing with plan documents and official notices.
2026 HSA limits loaded
$4,400 self-only · $8,750 family · $1,000 age-55 catch-up per eligible spouse.
Spouse B receives the remaining 50% when the shared family basic limit applies.
HDHP coverage
Select only coverage represented as HSA-eligible by the plan.
The calculator tests coverage on the first day of each selected month.
Other coverage
Do not enter a limited-purpose or qualifying post-deductible arrangement here.
Use this for other non-HDHP coverage you have already confirmed is disqualifying.
Age and contributions
Include deposits designated for 2026.
Employer deposits count toward this spouse's HSA limit.
Medicare Part A timing
Use the month on the Medicare or Social Security notice. A known month overrides the estimate below.
Estimate an effective month when it is not known
The estimate subtracts the expected retroactive months from the application month, but never goes earlier than the entered Medicare eligibility month.
Choose None when there is no planned or completed application in this window.
Retroactive premium-free Part A generally cannot start before Medicare eligibility. When None is selected, the estimate uses January 2026 as its earliest boundary.
The engine caps this estimate at six months. Actual enrollment history can produce a different date.
HDHP coverage
Select only coverage represented as HSA-eligible by the plan.
The calculator tests coverage on the first day of each selected month.
Other coverage
Do not enter a limited-purpose or qualifying post-deductible arrangement here.
Use the end of any grace-period, carryover, or plan coverage window. None is treated as December.
Use this for other non-HDHP coverage you have already confirmed is disqualifying.
Age and contributions
Include deposits designated for 2026.
Employer deposits count toward this spouse's HSA limit.
Medicare Part A timing
Use the month on the Medicare or Social Security notice. A known month overrides the estimate below.
Estimate an effective month when it is not known
The estimate subtracts the expected retroactive months from the application month, but never goes earlier than the entered Medicare eligibility month.
Choose None when there is no planned or completed application in this window.
Retroactive premium-free Part A generally cannot start before Medicare eligibility. When None is selected, the estimate uses January 2026 as its earliest boundary.
The engine caps this estimate at six months. Actual enrollment history can produce a different date.
At least one spouse is above that spouse’s prorated allocation
The month-by-month method produces a $5,858 household total under the entered facts. Results below keep each spouse's HSA, catch-up, and Medicare timing separate.
Household prorated limit
$5,858
Family basic allocation: 50% to Spouse A
Entered contributions
$6,000
Both spouses' employer and employee contributions
Prorated room
$0
Household total; verify each spouse separately below
Amount above prorated total
$142
Not a final excess determination; last-month-rule treatment may differ
Last-month-rule alternatives
$5,858
Combined comparison only; each spouse has a separate test
8 of 12 entered eligible months
Medicare timing
No Part A effective month is entered or estimated.
8 of 12 entered eligible months
Medicare timing
No Part A effective month is entered or estimated.
Each tile applies the HDHP, dependent-status, FSA/HRA, other-coverage, and Medicare facts entered for the first day of that month. “Passes screen” means only that none of the modeled disqualifiers was entered. The dollar amount is the engine's allocated monthly contribution limit, including a prorated catch-up when entered.
First-day-of-month screen and allocated monthly limit
8 eligible months
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Family HDHP
$364.58
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Family HDHP
$364.58
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Family HDHP
$0.00
Allocated monthly limit
Family HDHP
$0.00
Allocated monthly limit
Family HDHP
$0.00
Allocated monthly limit
Family HDHP
$0.00
Allocated monthly limit
First-day-of-month screen and allocated monthly limit
8 eligible months
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$366.67
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$364.58
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$364.58
Allocated monthly limit
No disqualifying fact included in this calculator is entered for this month.
Self-only HDHP
$0.00
Allocated monthly limit
Self-only HDHP
$0.00
Allocated monthly limit
Self-only HDHP
$0.00
Allocated monthly limit
Self-only HDHP
$0.00
Allocated monthly limit
The alternative is displayed only as a planning comparison. It can increase a spouse's amount when that spouse is an eligible individual on December 1, but it also creates a testing-period question that the prorated method does not.
The last-month-rule alternative does not increase this spouse's modeled amount under the entered facts.
Room under alternative: $0. Estimated excess under alternative: $1,071.
The last-month-rule alternative does not increase this spouse's modeled amount under the entered facts.
Room under alternative: $929. Estimated excess under alternative: $0.
For each spouse and month, the engine begins with the entered HDHP coverage and then screens for dependent status, that spouse's general-purpose FSA/HRA window, a spouse's FSA/HRA entered as covering them, other confirmed disqualifying coverage, and Medicare Part A. It applies the prorated basic limit and any age-55 catch-up only to months that pass that modeled screen.
A known Part A effective month always overrides the application-based estimate. Without a known month, the estimate moves backward by the entered retroactive period, capped at six months, but not before the entered Medicare eligibility month.
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HSA household planning guide
HSA contribution room can change month by month. A midyear HDHP change, a spouse’s general-purpose FSA, employer deposits, an age-55 catch-up, or retroactive Medicare Part A can all change the amount attributed to each spouse.
This planner keeps the two individual HSAs separate while showing the household’s shared family basic limit, a transparent month calendar, and an application-based Medicare estimate that can be replaced by the actual effective month.
Start with each spouse’s January HDHP type and enter the first month of any midyear change.
Enter general-purpose FSA or HRA coverage, whether it can reimburse the spouse, and any other coverage already confirmed as disqualifying.
Enter employer and employee contributions for each account, then choose how the shared family basic limit is allocated.
Use an official Part A effective month when available. Otherwise use the application estimate only as a date to verify.
A general-purpose health FSA or HRA that can reimburse a spouse’s medical expenses may be other coverage for that spouse, even if no reimbursement is requested. Limited-purpose and qualifying post-deductible arrangements can be different, so the plan document matters.
Premium-free Part A can begin retroactively when someone applies after becoming eligible. Medicare advises workers with HSAs to review contributions well before applying, and the actual effective date on the Medicare or Social Security notice should replace any generic six-month estimate.
The prorated method uses eligible months. The last-month rule can provide a larger alternative when a person is eligible on December 1, but the extra amount depends on remaining eligible through the applicable testing period. The tool shows the alternatives separately rather than choosing one.
This calculator is a fact-pattern organizer, not an HSA eligibility, excess-contribution, Medicare enrollment, or filing determination. Confirm HDHP status and FSA/HRA terms with the plan administrators, use the actual Part A effective notice, and review IRS Form 8889 instructions or qualified professional guidance before acting on a last-month-rule or excess estimate.
They can each contribute to an HSA only for months in which that spouse is an eligible individual. When the married-couple family rule applies, the spouses share one family basic limit and can allocate it between their HSAs; each eligible age-55 catch-up remains separate.
It can when the arrangement can reimburse your medical expenses. Enrollment or actual reimbursement is not necessarily the deciding fact, so verify who the plan can cover and whether it is general-purpose, limited-purpose, or post-deductible.
Yes. Employer and employee or personal contributions generally use the same annual contribution limit for that person, which is why the calculator adds them together.
The key planning date is the actual Part A effective month. Premium-free Part A may be retroactive, often by as much as six months but not before Medicare eligibility. Medicare advises HSA contributors to plan ahead before applying; use the official notice rather than relying solely on this estimate.
Medicare enrollment affects eligibility for new HSA contributions, not ownership of existing HSA funds. Existing funds can continue to be used for qualifying medical expenses under the applicable rules.
A person eligible on December 1 may be able to use the last-month rule instead of ordinary monthly proration. The extra amount generally depends on remaining an eligible individual through the end of the following calendar year, subject to statutory exceptions.
The monthly HSA contribution calculation generally looks to whether the person is an eligible individual on the first day of the month. The last-month rule is a separate alternative shown alongside that proration.
