Maximum TBC for Pension account is currently $1.9M any amounts over that incur the 15% tax on earnings.
It goes up to $2M 1st of July.
If your TBC increases in value after you set it up it still remains tax free.
Example, You set your Super Pension Account up a few years ago when the TBC was $1.7M and had $2.4M in Super
$1.7M went into your Pension account and you withdrew the minimum 4% and you had $700k in your Accunulation account.
Your TBC has risen to $2M now, It is still tax free. Your Accumulation account has risen also, it it is not tax free and tax has been paid on its earnings.