Why one extra dollar of income can matter when you receive GIS

For most taxpayers, an extra dollar of income costs somewhere between zero and fifty cents in tax. For someone receiving the Guaranteed Income Supplement, the arithmetic is different. The supplement is reduced as other income rises, by at least fifty cents for every dollar, and that is before any income tax. A withdrawal or a small pension that looks harmless on its own can cost a surprising share of itself in the following year’s GIS.

This sheet works through the reduction with the published October to December 2026 figures, and shows why the source of the dollar matters as much as its size.

What GIS is, in figures

The Guaranteed Income Supplement is a monthly, non-taxable benefit paid on top of Old Age Security to people with low income. Amounts are adjusted every quarter for the cost of living. For a single person receiving OAS, the published figures for October to December 2026 are:

Fifty cents on the dollar

The basic rule, as ESDC describes it, is that for every $2 of other income, the maximum benefit is reduced by $1. That is a 50% reduction rate. Below $10,496 of income there is an additional top-up portion that is also being phased out, so in that low band each extra dollar reduces the supplement by more than fifty cents. Above $10,496, the 50% rate applies until GIS reaches zero at the cut-off.

Couples are assessed on combined income, with their own maximums and cut-offs depending on whether the partner receives OAS, the Allowance or neither. The principle is the same; the figures differ.

The working: $2,000 from a RRIF

An illustrative single pensioner has $12,000 of income besides OAS: a CPP pension of $9,000 a year and a small workplace pension of $3,000. That is above the top-up band, so the 50% rate applies. In one year they take an extra $2,000 out of a RRIF:

Half of the withdrawal comes back out of the following year’s supplement. At this income level the basic personal amount and the age amount usually mean no federal tax is owed, so GIS is effectively the whole cost. That is the sense in which a GIS recipient faces one of the highest effective rates in the tax and benefit system.

The working: where the dollar comes from

Not every dollar counts the same. Employment and self-employment income get special treatment: the first $5,000 is excluded, and half of the next $10,000 is excluded too. TFSA withdrawals are not income at all. Here is the same illustrative pensioner with $8,000 of extra cash from three different sources:

The same $8,000 costs $4,000 of supplement in one case and nothing in another. That is why the question of where a GIS recipient’s spending money comes from has a number attached to it; we compare the account types in TFSA or RRSP after 65, and what the numbers tend to favour.

The one-year lag

GIS is based on the previous year’s income. ESDC’s own example: net income for 2023 determined GIS for the benefit year starting July 2024. So the cost of the RRIF withdrawal above shows up from the July after the tax year in which it was taken, and lasts twelve months. A one-off withdrawal reduces one benefit year; a recurring one reduces every year.

The lag can also run the other way. When income falls sharply, for example on stopping work or when a pension ends, Service Canada can in some cases look at an estimate of current-year income instead of last year’s. That is a question for Service Canada directly.

What counts and what does not

• Counts: CPP and QPP pensions, workplace pensions, RRIF and RRSP withdrawals, interest, dividends, the taxable part of capital gains, and employment income above the exemptions.
• Does not count: the OAS pension itself, the GIS itself, TFSA withdrawals and TFSA investment income.

Because CPP counts, each January’s CPP indexation nudges GIS down slightly for people who receive both, even as OAS and GIS are themselves adjusted for prices. The mechanics of that January increase are in what twenty years of indexation does to a CPP pension. Each year of work after starting CPP can also add a post-retirement benefit, which counts as CPP income.

Who this matters for, and what to check

• Anyone receiving GIS, or with income close enough to the cut-off to qualify in a low year.
• Anyone receiving GIS who is planning a RRIF withdrawal, a property sale or a lump sum: check which benefit year it will hit.
• Couples: the combined income test means one partner’s withdrawal affects both.
• Everyone on GIS: file a tax return every year. GIS is normally renewed automatically from it.

The short version

For a single GIS recipient above the top-up band, each extra dollar of countable income reduces the following year’s supplement by fifty cents; below it, by more. Employment income is partly exempt and TFSA withdrawals are not counted at all, so the same amount of cash can cost a great deal or nothing, depending on where it comes from.