I revised the November 22 spreadsheets for tax planning: “total gain percent.”
Posted on December 6, 2024

I revised the spreadsheets for tax planning that I included in this post two weeks ago. I corrected the math that calculates the taxable gain on sale of taxable securities. My taxable gain is much less than I previously calculated. These are the corrected sheets for single filer and married, joint filers.

Details:

Fidelity’s display of our taxable securities shows the total dollar gain (today’s price – cost basis) of shares and the “percent total gain.” I assume your broker has a similar display. That’s the gain in value relative to cost basis. If the value of my shares today is $180 and my cost basis is $100, I have a total gain of $80; my gain equals 80% of my cost basis.

For tax planning, I want the taxable gain on an amount sold: the gain relative to price. If I sold $180 today, my gain would be $80 or ~44% of the price. At 15% capital gain tax, my effective tax rate is 6.7%. I net 93.3% of the sales proceeds.

I corrected the cell to correctly translate “percent total gain” to the taxable percent of the sales proceeds. You can see more details on this spreadsheet. My taxable gain from sales will be lower. I have more room to convert traditional to Roth.

To be more precise, and perhaps result in lower taxable gain, I could estimate total taxable gain by adding up my cost basis of “selected shares” I wanted to sell.