An OAS deferral calculator estimates the higher monthly pension you could receive by starting Old Age Security (OAS) after age 65. Under the 2026 OAS rules, your pension increases by 0.6% for each month of deferral, with increases available for up to 60 months.
Calculate Your OAS Increase
You need two figures: the monthly OAS pension you would otherwise receive and the number of months you plan to delay.
Use these formulas:
Deferral increase = Number of months delayed × 0.6%
Higher monthly OAS = Starting monthly OAS × (1 + deferral increase)
The percentage calculation works out as follows:
| OAS start age | Months deferred | Increase |
|---|---|---|
| 65 | 0 | 0% |
| 66 | 12 | 7.2% |
| 67 | 24 | 14.4% |
| 68 | 36 | 21.6% |
| 69 | 48 | 28.8% |
| 70 | 60 | 36% |
The 2026 federal OAS rules do not provide any additional deferral increase after age 70. The same monthly formula is also established in the Old Age Security Act.
OAS Deferral Example Using the 2026 Maximum
For July to September 2026, the maximum OAS pension for someone aged 65 to 74 is $751.97 per month.
Using that amount as the starting point produces these estimates:
| Start age | Increase | Estimated monthly OAS |
|---|---|---|
| 65 | 0% | $751.97 |
| 66 | 7.2% | $806.11 |
| 67 | 14.4% | $860.25 |
| 68 | 21.6% | $914.40 |
| 69 | 28.8% | $968.54 |
| 70 | 36% | $1,022.68 |
These figures show the effect of deferral on the July to September 2026 maximum rather than predicting the actual dollar amount you will receive years from now. OAS rates are reviewed quarterly for inflation, so future base pension amounts can change. Our article on OAS inflation adjustments covers that separate calculation.
For example, someone entitled to $700 per month before a 30-month deferral would first calculate a deferral increase of 18%. Multiplying $700 by 1.18 gives an estimated monthly pension of $826, an increase of $126 per month.
The percentage increase applies to the pension you are entitled to receive, so using the maximum OAS amount in a calculator can overstate the result when your underlying pension is lower. You can estimate that underlying amount separately with our OAS calculator.
For the broader rules about choosing a later start date, see how OAS deferral works.
Questions About OAS Deferral Calculations
Does the deferral increase apply to a partial OAS pension?
Yes. The 2026 rules also provide the monthly deferral increase for a partial OAS pension. Enter the partial pension amount you are entitled to receive as the starting amount rather than the maximum pension.
Does turning 75 affect a pension that was previously increased through deferral?
Yes. OAS recipients receive an automatic 10% increase in the month after their 75th birthday under the 2026 rules. That age-based adjustment is separate from the increase earned by delaying the initial OAS start date.
Can you collect the Guaranteed Income Supplement while delaying OAS?
No. You cannot receive the Guaranteed Income Supplement (GIS) without receiving OAS. Someone who qualifies for GIS therefore needs to account for the GIS payments they would give up during the deferral period rather than judging the decision from the higher future OAS payment alone.
