There has been talk about capital gain indexing. How will capital gain indexing work?

Taxpayers would be able to increase their tax basis in capital assets by the rate of inflation between the purchase date and the time of sale.  Here is an example:

You bought stock in early 2008 for $20,000 and sold it for $35,000 in early 2018.  Using a common inflation measure, your original basis would jump to $23,227.  Absent indexing, you’d have a $15,000 capital gain ($35,000 – $20,000).  With indexing, your gain is $11,773 ($35,000 – $23,227), thus lowering your tax bill.

This is not law but has been discussed in Congress.

*Kiplinger Tax Letter