Your Old Age Security (OAS) pension is not calculated from your salary or how much you contributed while working. The starting point is the full OAS pension rate, then your Canadian residence history determines whether you receive the full amount or only part of it. Your starting age and later adjustments can also change the amount.
Under the 2026 OAS rules, a full pension generally requires 40 years of Canadian residence after age 18. A partial pension is calculated as your eligible years of Canadian residence divided by 40. Delaying OAS can increase that amount, while the pension receives a separate 10% increase after age 75.
How Your Years in Canada Determine Your OAS Pension
For most people, the central calculation is based on how many years they lived in Canada after turning 18. This is why two people of the same age can receive different OAS pensions even if they had similar careers or earnings.
Under the 2026 OAS calculation rules, 40 years of qualifying Canadian residence after age 18 generally gives you a full pension. There are special rules for some people with Canadian residence or immigration ties dating back to July 1, 1977, so 40 years is not an absolute requirement in every historical case. Eligibility itself is covered separately in our guide to who qualifies for OAS.
When you qualify for a partial pension, the Old Age Security Act uses this basic calculation:
Years of Canadian residence after age 18 ÷ 40 = percentage of the full OAS pension
For example, 20 eligible years produces 20/40ths, or 50%, of the applicable full pension. Thirty years produces 30/40ths, or 75%. The calculation uses completed years, with a period that is not a whole number of years rounded down to the lower whole year.
A detail worth knowing before you start a partial pension is that additional years of residence do not increase the residence fraction after the partial pension has been approved. Someone approved at 25/40ths does not gradually work up to 30/40ths simply by continuing to live in Canada for another five years. Our separate explanation of the OAS residency requirements covers which periods can count as Canadian residence.
Your OAS Starting Age Can Change the Calculation
The residence calculation establishes your full or partial pension entitlement, but the age at which you begin receiving OAS can increase it.
Under the 2026 deferral rules, your pension increases by 0.6% for each month you postpone it after becoming eligible. That works out to 7.2% for a full year and reaches a maximum 36% increase after 60 months. No additional deferral increase is earned after age 70.
The same deferral mechanism can apply to a partial pension. However, the calculation for someone with fewer than 40 years of Canadian residence has an extra wrinkle because waiting can potentially affect both the residence-based amount and the deferral calculation. The Old Age Security Act’s deferral provisions require the greatest applicable amount to be paid. That is one reason we would not simply multiply a newly accumulated residence fraction by the maximum deferral percentage and assume the result is correct.
The decision to postpone the pension has its own considerations, so we cover those separately in Can You Defer OAS?.
How the Full OAS Rate Changes Your Payment
The dollar value used in the calculation is not permanently fixed. OAS rates are reviewed four times a year, in January, April, July and October, based on changes in the Consumer Price Index. Rates can rise when the measured cost of living increases, but they do not fall when the cost of living decreases.
For July through September 2026, the maximum monthly OAS pension is $751.97 for people aged 65 to 74. Someone receiving a partial pension has the applicable fraction calculated against the full pension amount rather than receiving that maximum automatically. Because quarterly indexation can change the base rate, the dollar value of a partial pension can rise over time even though its residence fraction has been fixed.
The next quarterly adjustment is scheduled for October 2026. Our article on how OAS increases with inflation deals with that adjustment process rather than the individual pension calculation.
What Happens to the Calculation at Age 75
Under the 2026 OAS rules, the pension receives an automatic 10% increase beginning in the month after you turn 75. The increase applies to both full and partial OAS pensions and also applies after any eligible deferral increase.
For July through September 2026, this puts the maximum monthly pension for someone aged 75 or older at $827.17. The increase is built into the pension, so there is no separate application for it. Current maximum rates are tracked in our maximum OAS payment guide.
Why Your Income Can Change What You Actually Receive
Income does not replace the residence-based calculation used to establish your OAS pension. However, a sufficiently high net world income can cause some or all of the pension to be recovered through the OAS recovery tax.
For the July 2026 to June 2027 recovery period, the calculation uses your 2025 net world income. The 2025 threshold is $93,454, and the recovery is generally 15% of income above that threshold until the pension is fully recovered. The recovery-tax calculation is therefore separate from the residence, age and deferral calculations that establish the pension itself.
This difference matters when checking an unexpectedly low deposit. A person can qualify for a particular OAS pension amount but receive less because recovery tax is being withheld. We explain that calculation separately in our OAS clawback guide.
For a quick estimate, the official OAS Benefits Estimator uses your age, income and residence history to estimate your benefits. It currently uses the July to September 2026 rates.
Other Questions About How OAS Is Calculated
Do years lived in another country increase the fraction of a Canadian OAS pension?
Not normally. A social security agreement can allow periods in another country to help you meet the minimum requirement to qualify. However, the OAS amount is generally based on your actual years of Canadian residence after age 18. For example, someone with eight Canadian years who uses an agreement to qualify based on additional foreign periods can still receive 8/40ths rather than having those foreign years added to the pension fraction.
Does working more years increase your OAS pension?
Working itself does not increase the residence fraction. OAS is residence-based rather than contribution-based, unlike the Canada Pension Plan. Our CPP vs. OAS comparison explains how the two calculation systems differ.
Does your spouse’s income determine your OAS pension amount?
Your spouse’s income is not used to calculate the residence-based OAS pension entitlement. Household income becomes relevant to other income-tested benefits within the OAS program, particularly the Guaranteed Income Supplement, which has a separate calculation.
Can you calculate an exact partial OAS pension by multiplying today’s maximum by your years divided by 40?
That calculation can give you a useful starting estimate, but it may not reproduce your eventual payment when other applicable adjustments are involved. For an individualized estimate, enter your actual residence history and circumstances into the OAS Benefits Estimator rather than relying only on the simple fraction.
