Record Keeping For Tax Purposes

In Australia,
Capital Gains Tax Law came into operation some years ago, and coins over $100 value were mentioned in the tax schedules.
Nevertheless, there is no way either yourself of the Tax Office can prove or disprove if the coin was bought before or after Capital Gains Tax Law came into operation.

In this regard, that makes the Capital Gains Tax law in relation to coins unworkable.
Works much better in relation to real estate deals, where sales documetation has always been recorded.

I am not current on all my tax information so please don't take what I say as gospel, but as food for thought.

If you decide that your children will inherit your coin collection then the cost basis for your collection becomes the fair market value of the collection on the day you die. For example if you paid $1000 for your coins that would be your cost basis at the time that you sold them. However, if you held on to your collection and at the time of your death your collection was inherited by your children and was worth $10,000, then that would be the cost basis for your children. So, if your children sold the collection the very next day they would walk away tax free.