Three Percentage Mistakes That Delay a Cosmetic Filing

You've got your formula, you're ready to file the CNF, and then the percentages trip you up. Not the ingredients themselves, just how you wrote the numbers. This happens more than you'd think, and it's almost always one of three patterns.

Mistake one: filing the blend percentage instead of the real concentration

Say your preservative is a supplier blend at 1% of your finished product, and that blend is 20% phenoxyethanol. If you list phenoxyethanol at 1%, you've just overstated it fivefold on paper (the real number is 0.2%). This looks small until you're near a restricted-use ceiling, at which point a fake-high number can make a perfectly fine formula look like it's breaking a limit that it isn't anywhere near.

The fix is mechanical: multiply the component's percentage in the blend by the blend's use level in your product. Do this for every raw material that's actually a blend, not a single substance. Fragrance oils, some botanical extracts, and most preservative systems are the usual offenders.

Mistake two: reporting a range that doesn't match your batch records

Health Canada lets you file a concentration range instead of a single number, which is genuinely useful if you tweak a formula slightly between batches. The mistake is filing a range that's wider than what you actually produce, "just to be safe." If your batch records show 0.4% to 0.6% and you file 0 to 2%, that gap between paper and practice is exactly what gets a filing questioned if it's ever reviewed against your records.

Keep the range tight and honest:

• Match it to your actual production tolerance, not a hypothetical future one
• Re-file an amendment if you genuinely widen the range later
• Don't use a wide range to avoid re-filing for small formula tweaks; that's what amendments are for

Mistake three: rounding that erases a meaningful digit

At low concentrations, rounding matters. A fragrance allergen sitting at 0.0095% is under the 0.001% leave-on disclosure trigger by a wide margin, so that's fine to round. But an ingredient sitting at 0.011% rounded down to "0.01%" can quietly cross a threshold depending on which one applies. Restricted substances with a hard ceiling deserve at least two significant figures, not a tidy round number picked for readability.

Situation	Risky rounding	Better practice
Allergen near the 0.001% trigger	"under 0.01%"	State the actual measured or calculated value
Restricted substance near its ceiling	"approx. 1%"	Carry the real decimal from your batch sheet
Blend component	Blend % only	Blend % multiplied by use level

Why these three keep recurring

They all come from the same root cause: treating the CNF percentage field as a formality instead of a real number tied to your batch record. It isn't pre-market approval, but it's still a legal notification, and the number you type is the number that represents your product if anyone ever asks. Health Canada's Cosmetic Ingredient Hotlist sets prohibited and restricted concentrations, and if your filed percentage doesn't reflect the real math, you're not actually screening against those limits, you're screening against a guess.

A decent habit: before you file, pull your batch sheet and re-derive every percentage from scratch rather than copying what a supplier document or an old filing says. It takes ten extra minutes and it's the single best way to catch a blend-expansion error or a stale range before it becomes a filing that needs correcting.

This is also the exact math Cosmetic Comply automates when you upload an ingredient list. It expands supplier blends down to their real components, carries the percentages through, and screens each one against the Hotlist with a confidence score before a human reviewer signs off, so the number that ends up on your CNF is the one your batch actually supports.