Incorporation costs are considered an Asset for accounting purposes, so they would generally appear on your Balance Sheet (lets say GIFI code 2018 if you were transferring to the Schedule 100).
Line 418 on the Schedule 1 is a manual entry that allows you to deduct for tax purposes an amount of up to $3,000 for incorporation costs under the assumption you have recorded the incorporation fees on your balance sheet (Schedule 100). If the incorporation costs are over $3,000 then you claim $3,000 on line 418 of schedule 1 and are allowed to put the remaining balance on Schedule 8 as a class 14.1 asset.
If you have deducted the Incorporation costs on your financial statements then you would not use line 418 of the Schedule 1 or else you would be deducting the incorporation fees twice.