I have a flex provision to "juice" my DB pension as you describe above with bridging and indexing benefits. I asked my Payroll department how this works and they said the following:
So for me I can contribute 3% of my pay, to a max of $192.69 (bi-weekly). Sounds like 3% is the magic number, and I think a few others have said as well on this forum. I've started a thread about this 2 years ago I will try and dig it up later and link it here.There are very strict rules surrounding contribution limits and all are set by CRA. The 3% maxes out at 192.69.
The $3,500 relates to contributions for years of service prior to 1990 and it is the maximum amount that is tax deductible in one year (whereas for contributions for 1990 and later the full contribution is tax deductible)
If we (Payroll) do our job properly you cannot over contribute.
I hope this helps but ECO is complicated so let me know if you have other questions