2027 Social Security check calculator: COLA minus Part B
Enter your benefit and a 2027 COLA scenario; the calculator applies the dime rounding, the projected $209.50 Part B premium, hold-harmless and W-4V withholding to show the real deposit.
Last updated:
Your benefit, the COLA scenario and your deductions
| Line | 2026 | 2027 | Change |
|---|---|---|---|
| Gross benefit | $2,000.00 | $2,068.00 | +$68.00 |
| Part B premium | −$202.90 | −$209.50 | −$6.60 |
| Federal withholding (0%) | −$0.00 | −$0.00 | −$0.00 |
| Deposit | $1,797.10 | $1,858.50 | +$61.40 |
- Part B absorbs 9.7% of the announced raise.
- Over a year, the deposit rises by $736.80 ($816.00 announced).
- Hold-harmless does not trigger: the COLA ($68.00) covers the projected premium increase ($6.60).
Every October the Social Security Administration announces one percentage, and every January retirees discover that their deposit did not rise by that percentage. The gap is not a mistake. Three deductions sit between the announced cost-of-living adjustment and the money that lands in the bank, and each one is a fixed rule you can compute in advance. This calculator does exactly that for the 2027 adjustment, using the mechanics documented in our guide to the 2027 COLA versus the Part B premium and the range currently carried by the 2027 COLA tracker.
What the calculator is computing
It starts from your gross 2026 benefit and applies the COLA percentage you choose. The result is rounded down to the next lower multiple of ten cents, because 42 U.S.C. § 415(i) requires it — never up, never to the nearest cent. From that 2027 gross benefit it subtracts the Medicare Part B premium: $202.90 for 2026, the figure CMS set in the Federal Register on November 19, 2025, and for 2027 the $209.50 projected in Table V.E2 of the 2026 Medicare Trustees Report. That projection is editable on purpose. The Trustees' row for 2026 matched the CMS announcement to the cent, but the prior year's report was $3.60 too high, so the honest reading of $209.50 is "the best planning number until November", not a fact.
If you elected voluntary federal withholding with Form W-4V, the calculator applies the 7, 10, 12 or 22 percent you chose to the gross benefit in both years. Because the percentage is fixed and the benefit grows, the dollar amount withheld grows too, and that growth comes out of the raise. The withholding rules for Social Security differ from the W-4P steps a pension uses; our guide to withholding on Social Security and pensions covers both forms.
The hold-harmless check
Section 1839(f) of the Social Security Act, at 42 U.S.C. § 1395r(f), protects beneficiaries whose Part B premium is deducted from their check from seeing the dollar amount of that check fall because the premium rose faster than the COLA. When the box is ticked and your dollar COLA is smaller than the projected premium increase, the calculator caps the increase at the COLA and flags it. With a $6.60 projected increase and a 3.4 percent COLA, only benefits under roughly $194 a month would trigger the protection, which is why the flag stays quiet for almost everyone in 2027 — the opposite of years like 2016 and 2017, when a near-zero COLA met a large premium jump. The provision does not reach people paying an IRMAA surcharge, people new to Part B, or people billed for the premium directly; our guide to the hold-harmless provision works through the threshold arithmetic year by year.
How to read the results
The three headline figures are the announced raise, the real increase in the deposit, and the effective raise measured on the net deposit rather than on the gross benefit. The table beneath them shows each line for 2026 and 2027 so you can see where the money went. The share of the raise that Part B absorbs is the number worth remembering: on a $1,200 benefit with a 3.4 percent COLA and the projected premium, it is about 16 percent; on $3,000 it is about 6 percent. The premium increase is a flat dollar amount, so the smaller the check, the larger the bite. A bigger COLA shrinks that share mechanically, because the premium increase stays fixed while the raise grows around it.
Two figures the calculator does not show are just as relevant. If your income crosses one of the Medicare income thresholds, an IRMAA surcharge is added to the standard premium — add it to the 2027 premium field to approximate the effect, and check the 2027 IRMAA brackets projection for the tiers. And the new amount arrives on a schedule, not all at once: the January 2027 payment dates by birth-date group are in our guide to the first 2027 COLA payment date.
What changes in October and November
The COLA itself becomes known in mid-October 2026, when the Bureau of Labor Statistics publishes the September CPI-W and the Social Security Administration announces the adjustment. The Part B premium follows in November, when CMS publishes the 2027 rates. When either number lands, type it into the corresponding field: the calculator's structure does not change, only its inputs. Until then, the tracker's center of range and the Trustees' projection are the best available planning numbers, and the difference between the high and low scenarios on a typical benefit is a few dollars a month — small enough that the account you deposit it into matters more than the exact percentage.
Frequently asked
Why is the 2027 deposit increase smaller than my benefit times the COLA?
Three things happen after the percentage is applied. The new benefit is rounded down to the next lower dime under 42 U.S.C. § 415(i). The Part B premium, a flat dollar amount, is deducted before the money is sent, and any increase in that premium comes straight out of the raise. If you elected federal withholding on Form W-4V, that percentage is applied to the larger gross benefit, so withholding also grows. The calculator applies all three in that order.
Where do the $202.90 and $209.50 Part B figures come from?
The 2026 standard premium of $202.90 was set by CMS in the Federal Register on November 19, 2025. The $209.50 figure for 2027 is the projection in Table V.E2 of the 2026 Medicare Trustees Report; CMS will publish the actual 2027 premium in November 2026. The input is editable so you can replace the projection with the official number the day it is announced.
What is hold-harmless and does the calculator apply it?
Under Section 1839(f) of the Social Security Act, a beneficiary whose Part B premium is deducted from a Social Security check cannot see the dollar amount of that check fall because of a premium increase: the increase is capped at the dollar amount of the COLA. It does not apply to people who pay an IRMAA surcharge, who are new to Part B, or whose premium is billed separately. The calculator applies the cap when the box is ticked and the COLA in dollars is smaller than the premium increase, and tells you when it did.
Does the calculator handle IRMAA, Part D or Medicare Advantage premiums?
No. It models only the standard Part B premium. If your income puts you in an IRMAA tier, add the surcharge to the 2027 premium field to approximate the effect, and see our 2027 IRMAA brackets projection for the tiers. Part D and Medicare Advantage premiums vary by plan and are outside the scope.
Why does the calculator show cents when my deposit is a whole dollar?
The Social Security Administration rounds the amount actually paid down to the next lower whole dollar after the Medicare deduction, so a computed $1,646.30 arrives as $1,646. The calculator keeps the cents so the 2026 and 2027 lines can be compared exactly and so the numbers match the worked examples in our COLA-versus-Part-B guide.
When will I know the real 2027 COLA?
The Social Security Administration announces it in mid-October 2026, once the Bureau of Labor Statistics publishes the September CPI-W. Our tracker follows the three months that set it and narrows the range with each release. The first check paying the new amount is the January 2027 payment, dated by your birth-date group.