What the Same Medigap Plan G Costs in Alameda and Contra Costa: 2026 Rates From All 19 Carriers

Key findings

• The spread is real money. At 65, Plan G runs from $1,998 a year (about $167 a month) at the low end to $3,851 a year (about $321 a month) at the high end. That is $1,853 a year for benefits that are identical by law.
• The gap grows with age. At 75, the same comparison runs from $2,552 to $5,446 a year, a $2,894 annual difference, and the ratio between the most and least expensive carrier widens from 1.9 to 2.1.
• High Deductible Plan G is the quiet bargain of the table. 8 carriers offer it here, from $525 a year at 65, about $44 a month, in exchange for a higher annual deductible before the plan pays.
• Plan N runs from $1,369 to $2,871 a year at 65, a 2.1 to 1 spread against 1.9 to 1 for Plan G, with small copays and possible Part B excess charges as the tradeoff for the lower premium.
• 18 of the 19 carriers use attained age rating, meaning the premium climbs as you get older on top of any rate increases. Only Transamerica Life uses issue age rating in this market, an approach that often costs more at purchase but does not add age based increases afterward.
• Blue Shield of California, listed by CDI as California Physicians Service, charges $2,388 a year for Plan G at 65 here, and Anthem Blue Cross, listed as Blue Cross of California, charges $2,367. 6 carriers in the table charge less than both.
• Compared with our Los Angeles table, 3 of the 19 carriers charge exactly the same for Plan G at 65 here. The lowest Plan G at 65 here is $1,998, against $2,245 in Los Angeles, and the highest is $3,851, against $4,517.
• California's birthday rule makes this table actionable. Every year, in a window starting on your birthday, you can switch to another carrier's plan with equal or lesser benefits with no health questions, so a Plan G holder paying near the top of this table is never locked in.

Which ZIP codes this table covers

Each carrier sets its own rating regions, so one county can have more than one price list. We grouped the 91 Alameda and Contra Costa ZIP codes that returned CDI results into rate areas, where every carrier charges the same; the grouping is ours, not a CDI or carrier designation. The table above is rate area A.

Rate area A, the table above: about 73% of residents 65 and older in the ZIP codes we checked

ZIP codes: 94501, 94502, 94506, 94507, 94509, 94511, 94513, 94514, 94516, 94517, 94518, 94519, 94520, 94521, 94523, 94525, 94526, 94528, 94530, 94531, 94536, 94538, 94539, 94541, 94542, 94544, 94545, 94546, 94547, 94548, 94549, 94550, 94551, 94552, 94553, 94555, 94556, 94560, 94561, 94563, 94564, 94565, 94566, 94568, 94569, 94572, 94575, 94577, 94578, 94579, 94580, 94582, 94583, 94586, 94587, 94588, 94595, 94596, 94597, 94598

Rate area B: about 15% of residents 65 and older in the ZIP codes we checked

ZIP codes: 94601, 94602, 94603, 94605, 94606, 94607, 94608, 94609, 94610, 94611, 94612, 94613, 94618, 94619, 94621

Rate area C: about 11% of residents 65 and older in the ZIP codes we checked

ZIP codes: 94702, 94703, 94704, 94705, 94706, 94707, 94708, 94709, 94710, 94720, 94801, 94803, 94804, 94805, 94806

Plan G at 65 where the price changes inside the two counties

• In rate area B, 5 carriers charge more for Plan G at 65 than in rate area A.
• In rate area C, 4 carriers charge more for Plan G at 65 than in rate area A.
• Every other carrier charges the same for Plan G at 65 in all of these rate areas.

In 1 more ZIP code (94505), at least one carrier's price differs again. If your ZIP code is one of those, or is not listed on this page, call us and we will look up its rates.

Methodology

We retrieved these premiums from the California Department of Insurance 2026 Guide On Medicare Supplement Insurance, the regulator's own comparison tool, on October 26, 2026, for Alameda and Contra Costa, individual policies, non tobacco rates. We ran the CDI tool at age 65 for every ZIP code listed on this page, and at ages 70 and 75 for at least one ZIP code in every carrier rating region, read every result page with two independent parsers, and kept a figure only when both agreed; every ZIP code in the same carrier rating region returned identical rates. Premiums shown are annual amounts as filed with and approved by the regulator; monthly figures quoted in the findings are those amounts divided by twelve. Carriers appear under their legal filing names: California Physicians Service is Blue Shield of California, and Blue Cross of California is Anthem Blue Cross. Rates can change through carrier rate actions and differ by ZIP code, age, tobacco status, and household discounts, so treat this table as the map of the market rather than a quote. We are an independent agency and do not sell every carrier listed; the table includes every carrier the CDI tool lists for these ZIP codes regardless of whether we represent them. CDI lists UnitedHealthcare Insurance Company under its separate group policy type, so it is not in this individual policy table.

This table is published under a Creative Commons BY 4.0 license. Journalists and researchers may reuse it with attribution to Goulson Insurance Services and a link to this page.

Already have a Medigap policy and paying near the top of the table? California's birthday rule lets you move to equal or lesser benefits each year with no medical underwriting. Learn more on our California birthday rule page

Plan G rates in other California regions

The same CDI comparison for other parts of the state: every carrier, Plan G at 65, 70, and 75, plus Plan N and High Deductible G.

• Medigap Plan G Rates in Los Angeles
• Medigap Plan G Rates in San Diego County
• Medigap Plan G Rates in Orange County
• Medigap Plan G Rates in Riverside County
• Medigap Plan G Rates in Santa Clara County
• Medigap Plan G Rates in Ventura County