Here is a question worth a few hundred points a year across the country. A student has six H1s and a H6 in higher level maths. How much is the maths bonus worth to them?
Most calculators online say 25. The answer is nothing.
Where the points go
Higher level maths at H6 or better earns 25 bonus points. The rule that decides what they are worth is where they land: the bonus is added to the maths result, and the best six subjects are chosen afterwards.
So in that example, the H6 in maths is worth 46 plus 25, which is 71. Then the best six are picked. Six H1s at 100 each are all ahead of 71, so maths does not make the six, and the 71 never enters the total. The student has 600 points, exactly as they would have without ever sitting higher maths.
A calculator that adds 25 at the end tells them 625. That is not a rounding error, it is a wrong answer at the top of the scale.
Three outcomes, not one
Work through the possibilities and the bonus lands in one of three places.
It counts in full. Maths was already among your best six. Add 25 and move on. This is the case everyone assumes.
It counts for less than 25. Maths was not in your six, and the bonus pulls it in. Say five H2s, a H5 in maths, and a H4 elsewhere. Without the bonus, your sixth slot is the H4 at 66. With it, maths is 81 and takes the slot instead. You gained 15, not 25, because the H4 you displaced was already counting.
It counts for nothing. Maths misses the six even with the bonus, as in the opening example.
The second case is the one nobody talks about, and it is common. Any student whose maths is mid table among their subjects is in it.
Why it matters in August
A student comparing 625 against 600 is making a different decision about their list than a student who knows the truth. Overstating points by 25 near a cut-off is enough to change which course somebody puts first.
The calculator on this site picks the best six after the bonus is applied, and then tells you which of the three cases you are in and what the bonus was worth to you. If it says nothing, that is the honest answer, and it is better to know it in January than to find out on offer day.
The rule itself is published in the CAO's own material on bonus points for higher level mathematics. It is not hidden. It is just easier to write a calculator that ignores it.