Celiac Sentry
Celiac Sentry
The per-gram comparison method is how the CRA calculates the eligible incremental cost of gluten-free food for Canadians with Celiac disease. If you've tried to do this manually, you know it's tedious — but understanding how it works is essential to making sure your claim is accurate and audit-ready.
The obvious approach — just subtract the regular price from the GF price — doesn't work because package sizes are usually different. A regular loaf of bread might be 675g, while the GF equivalent is 450g. Comparing raw prices would give you an inaccurate result.
The per-gram method normalizes everything to a common unit (price per 100g), making the comparison fair regardless of package size differences.
Divide the price of the GF product by its weight in grams, then multiply by 100.
Example: GF bread at $6.99 for 450g → $6.99 ÷ 450 × 100 = $1.553 per 100g
Do the same for the regular (non-GF) equivalent. Use a defensible reference price — Statistics Canada provincial averages are ideal.
Example: Regular bread at $3.49 for 675g → $3.49 ÷ 675 × 100 = $0.517 per 100g
Subtract the regular price per 100g from the GF price per 100g.
Example: $1.553 − $0.517 = $1.036 per 100g
Multiply the difference per 100g by the number of 100g units in your GF package.
Example: 450g ÷ 100 = 4.5 units → $1.036 × 4.5 = $4.66 eligible
| Product | GF Price/Weight | Regular Price/Weight | Eligible Amount |
|---|---|---|---|
| Bread | $6.99 / 450g | $3.49 / 675g | ~$4.66 |
| Pasta | $5.99 / 340g | $1.49 / 900g | ~$5.41 |
| Flour | $8.99 / 1kg | $4.99 / 2kg | ~$6.50 |
| Cereal | $6.49 / 300g | $4.99 / 500g | ~$3.50 |
| Crackers | $4.99 / 150g | $2.99 / 450g | ~$4.00 |
These are illustrative examples using approximate prices. Your actual eligible amounts will vary based on your specific purchases and your province's reference prices.
The CRA expects you to use a documented, defensible source for your regular equivalent prices. The two main options:
Statistics Canada publishes monthly average retail prices for food products by province. This is the most defensible source for CRA purposes because it's an official government data source, it's provincial (accounts for regional price differences), and it's publicly available and verifiable.
Source: Statistics Canada Table 18-10-0245-01
You can also photograph the regular equivalent's shelf price tag at the store where you purchase your GF product. This is highly defensible because it's a direct, contemporaneous comparison at the same store.
It's easy to underestimate how much this adds up to over a year. Consider a typical single person with Celiac disease buying GF staples weekly:
| Product | Frequency | Est. Eligible/Purchase | Annual Total |
|---|---|---|---|
| Bread (1 loaf/week) | 52x/year | ~$4.50 | ~$234 |
| Pasta (2x/month) | 24x/year | ~$5.00 | ~$120 |
| Flour (monthly) | 12x/year | ~$6.50 | ~$78 |
| Cereal (2x/month) | 24x/year | ~$3.50 | ~$84 |
| Crackers/snacks (2x/month) | 24x/year | ~$4.00 | ~$96 |
| Approximate Total | ~$612/year |
And that's a conservative estimate for one person, covering only the most common staples. A family with multiple Celiac members, or someone who buys a wider range of GF products, could have significantly higher eligible amounts.
Every single GF product purchase requires this calculation. For someone buying 20-30 different GF products across a week's grocery shop, that's 20-30 individual calculations — then multiplied across 52 weeks. Most people find the effort-to-reward ratio too high and simply don't claim.
That's the problem Celiac Sentry was built to solve.
Celiac Sentry scans your grocery receipt, automatically identifies GF items, and calculates the per-gram comparison using Statistics Canada provincial reference prices — in seconds, not hours.
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