The PBO has recently released a report entitled Cost Estimate of Bill C-239: An Act to amend the Income Tax Act (Charitable Gifts).  Bill C-239 is a private members bill by MP Ted Falk to increase donation tax incentives to match the tax rates given for political donations to charitable donations, but with none of the limits that apply to the amount that you can donate to political parties.  The report is well worth reading.  It describes the very high cost of passing this private members bill even if more funds are not donated to charity.

In the PBO report Cost Estimate of Bill C-239: An Act to amend the Income Tax Act (Charitable Gifts) it notes that the cost of this bill could be over $2 billion per year.