How to only sell shares(index funds) with long term gains after mid year conversion to vanguard admiral class?

Question

I've never sold in a taxable account before so please bear with me.

I bought VGTSX more than a year ago and then upgraded to admiral class last year(and bought more). Now, I would like to sell some of my shares, while avoiding the short-term cap gain tax.

On vanguard I set my fund to FIFO, but this is confusing to me since I converted VGTSX to VTSAX halfway last year. If I didn't do the conversion, I could easily sell the X number of shares I bought initially. But now, after the conversion I am not sure what to do.

Does Vanguard have an easy way for me to determine how much shares I can safely sell?

Answer 1

Converting share class is not a taxable event, so each lot of your converted shares should still have its original basis and holding period. If you have the records, multiply each purchase quantity by the ratio of (total new shares / total old shares) at the conversion (and round, apparently to 3 decimals; maybe sell slightly less than you compute in case your arithmetic differs from theirs). IIRC under MyAccounts/CostBasis it has an option to show the individual lots, but I no longer have an open holding to verify this.

FYI if you choose to use the average method for basis for a mutual fund, your holding period is still computed FIFO.