Romulan maths
Romulus,
What happened to the 01 July 16 increase of 3%?
What made you think that the 1.5% would apply to your example salary of $104K rather than the increased salary of $107120?
The starting point should be the salary payable pre-July 16, which I think you meant to be $104000.
On 01 July 16, that salary would increase by 3% to $107120.
On 01 July 17, that salary would increase by 3% to $110334.
On 01 July 18, that salary would increase by 1.5% to $111989.
That new post-July 18 rate would apply regardless of how long it is paid. December 18 is just the end of the Agreement, so the post-July 18 rate would continue to get paid until a new deal is negotiated.
The key problem is the belief that the 1.5% is justified as if it is the same as 3% for only 6 months - it is not!
For the period July 18 to December 18 you will get paid $111989/2 = $55995 (rounded up). Over the same period to December 18 , a 3% pay rise would have yielded $113644/2 = $56822, a difference of +$827.
I reckon the easiest way to think about it is simply that the agreement gives a pay rise of $111989/$104000 = 7.68% over the life of the agreement. While the nominal 3+3+3 would yield 9.27% by comparison, I do not believe that that was on the table.