How OAS Deferral Works
Old Age Security starts at 65 by default. But you can delay the start date — up to age 70 — and receive a larger monthly payment for the rest of your life. Every month you defer past 65 adds 0.6% to your base OAS amount.
Defer all five years to 70, and that's 60 months × 0.6% = 36% more per month, permanently. The increase is applied to whatever the maximum OAS rate is when you start collecting — it's not locked in at your 65th birthday rate.
2025 OAS: What the Numbers Look Like
Maximum OAS at 65 (2025): ~$727.67/month
Maximum OAS at 70 (with full deferral): ~$989.63/month
Difference: ~$261.96/month | ~$3,143.52/year
That's real money — if you live long enough to collect it.
The OAS amount above is the maximum for seniors who have lived in Canada for 40+ years after age 18. Partial OAS (for those with fewer than 40 years of Canadian residency) scales proportionally, but the 36% deferral boost still applies to your personal amount.
The Break-Even Math
When you defer OAS, you give up five years of payments in exchange for a higher amount afterward. The break-even point is when the total cumulative payments from the deferred OAS catch up to what you'd have received starting at 65.
Break-Even Calculation
Foregone OAS (age 65–70): $727.67 × 60 months = ~$43,660
Extra monthly gain at 70: ~$261.96/month
Months to recover: $43,660 ÷ $261.96 = ~167 months (~13.9 years)
Break-even age: 70 + 13.9 years = approximately age 83–84
If you live past 84, deferring OAS puts more money in your pocket over your lifetime.
This calculation ignores inflation indexing and the time value of money. OAS is indexed to CPI quarterly, so both the "take at 65" and "defer to 70" scenarios grow with inflation — the break-even analysis holds roughly the same in real terms.
If you account for the opportunity cost of investing that foregone OAS at a modest return (say 4–5%), the break-even age pushes closer to 85–86. Still well within a realistic planning horizon for a healthy 65-year-old.
Who Should Consider Deferring OAS
Good candidates for deferral:
High-income retirees facing OAS clawback. In 2025, the OAS clawback (Recovery Tax) kicks in at net income of $93,208. Above that, you repay $0.15 for every dollar earned. If you have a defined benefit pension, RRIF withdrawals, or rental income pushing you above this threshold at 65, collecting OAS just means clawing most of it back. Deferring until income drops below the threshold — or until RRIF drawdowns begin forcing income anyway — can preserve the full benefit.
People with DB pensions or substantial non-registered income. If you don't need OAS income at 65, deferring costs you nothing in terms of lifestyle. You're essentially buying longevity insurance with money you weren't spending.
People in good health with family history of longevity. The break-even math only pays off if you live past 82–84. A 65-year-old in excellent health has a reasonable probability of that. Statistics Canada data puts life expectancy for a 65-year-old Canadian at roughly 85–87 years on average — meaning the median person does come out ahead by deferring.
Who Should NOT Defer OAS
Don't defer if any of these apply:
Poor health or family history of shorter lifespan. The math requires living past 83. If your health situation makes that unlikely, taking OAS at 65 — even at a lower rate — means more total money collected.
Low income where every dollar counts. If you need the income at 65, that ends the conversation. A smaller guaranteed payment starting now beats a larger hypothetical one later.
GIS eligibility — the most important exception. The Guaranteed Income Supplement tops up OAS for low-income seniors. GIS is income-tested and non-taxable. If you defer OAS at 65 but your income is low enough to qualify for GIS, you're leaving GIS money uncollected for five years — and GIS payments do not defer or accumulate. Once those years pass, they're gone. In most cases, deferring OAS while GIS-eligible is a costly mistake that most financial calculators miss.
The GIS Interaction — A Critical Detail
GIS pays up to ~$1,086/month (2025) on top of OAS for seniors with very low income. It's income-tested — the higher your income, the less GIS you receive. OAS itself counts as income for GIS purposes, but GIS is worth pursuing for low-income Canadians.
If your net income at 65 is below ~$22,056 (single senior), you may qualify for full or partial GIS. Deferring OAS means you cannot receive GIS during those deferred years because GIS requires you to be receiving OAS. You don't defer GIS — you simply don't get it.
For a low-income senior, GIS + OAS at 65 can provide $1,800+/month tax-free. Deferring to collect a marginally higher OAS at 70 while forgoing five years of GIS almost never makes financial sense. The numbers rarely work out.
CPP vs. OAS Deferral: How They Compare
Many Canadians are simultaneously deciding whether to defer CPP and OAS. These are separate decisions, but worth understanding together as part of a broader retirement income plan.
| Feature | CPP Deferral | OAS Deferral |
|---|---|---|
| Default start age | 65 (can start at 60) | 65 |
| Maximum deferral age | 70 | 70 |
| Bonus per month deferred (post-65) | 0.7%/month (8.4%/year) | 0.6%/month (7.2%/year) |
| Total gain at 70 vs 65 | 42% | 36% |
| Break-even age (approximate) | ~82–83 | ~83–84 |
| Income-tested? | No | Yes (clawback above $93,208) |
Both deferral strategies are mathematically similar. CPP deferral grows slightly faster (8.4%/year vs 7.2%/year for OAS). For healthy, high-income retirees, deferring both to 70 is often the optimal strategy — it minimizes early withdrawals, reduces clawback risk, and maximizes guaranteed lifetime income.
For people with a shorter expected lifespan or pressing income needs, taking CPP early and deferring OAS — or taking both at 65 — may make more sense. There's no universal right answer.
Couples: Two Independent Decisions
Each person in a couple makes their own OAS deferral decision separately. There's no spousal benefit or joint application for OAS — it's an individual program based on each person's Canadian residency history.
This matters for retirement planning. A couple might strategically decide that the higher-income partner defers OAS (to avoid clawback) while the lower-income partner takes OAS at 65 (or earlier if near the GIS threshold). Coordinating these decisions with your overall RRSP drawdown strategy and TFSA usage can meaningfully affect lifetime after-tax income.
How to Apply — and When
OAS does not start automatically. You need to apply through Service Canada — either online via My Account, by mail, or in person at a Service Canada centre. You can apply up to 11 months before your desired start date.
If you want OAS to start at 70, apply at age 69 and 1 month. Don't wait until your 70th birthday — payments start the month after your application is approved, and retroactive payments are limited. Missing your application window means missing money you can't recover.
If you haven't applied and are already past 65, you can receive up to 11 months of retroactive OAS payments. But note: retroactive payments are taxable income in the year received, which may have clawback implications. In some cases, you can elect to have the retroactive payment taxed in the year it was earned (using the T1198 form) — worth discussing with a tax professional.
Don't forget: Deferring OAS does not affect your eligibility for the Age Amount tax credit (line 30100), which is available at age 65 regardless of when you start OAS. It also doesn't affect your ability to make TFSA contributions — which continue based on your age and residency, not your pension status.
Quick Decision Framework
- High income + good health: Defer to 70. The clawback math and longevity odds both favour it.
- Moderate income, healthy: Run your personal numbers. Break-even at 83–84 is achievable. Deferring is often worth it.
- Low income, GIS-eligible: Do not defer. Take OAS at 65 and collect every year of GIS you're entitled to.
- Poor health or uncertain longevity: Take OAS at 65. The break-even is too far out to bet on.
- Need the income: Take it. Cash flow now beats hypothetical optimization later.
The deferral decision intersects with your full retirement income picture — RRSP/RRIF balances, CPP timing, non-registered investments, and tax bracket management. It's one lever in a larger plan, not a standalone choice.