That is correct. The 83(b) declaration is only valid for 'restricted stock' which is stock that is granted to you rather than as an option to buy.
In those situations you acquire the 'right' to the stock over time (this is called vesting). And when you vest stock the IRS treats it like income and it gets added to your W2 as such.
The 83(b) election allows you to take the entire tax hit immediately even though you don't have the ownership rights on the stock yet. You need to come up with the tax payment but since you "own" the stock even when it vests you won't pay additional taxes, and your ownership starts the clock on long term gains (vs short term gains).
If the stock is going up an 83b can save you some money, if it is going down it makes it more complicated (you can write off up to $3,000 of "loss" per year of stock which is worth less than the 83b election price. I got to do that for just over 10 years on my dot com era 83b stock election.
Generally places like Facebook or Google will sell some of your RSUs as they vest to cover the tax hit so its pretty invisible to you.
Note that there are a few alternatives to this. Fred Wilson, from Union Square Ventures (who pg wrote about it here[1]), gave a 1 hour class on the subject[2]. He covered tax and mechanisms to avoid taking unecessary invetment gains tax.
Another great post on this subject (which may be a bit dated nowadays) was this one[3]. Hacker News startup lawyer had also some great comments on its corresponding HN thread[4]. Note that it embeds the Introduction to Stock Options[5] that also had an amazing discussion on HN a few years ago[6]
In those situations you acquire the 'right' to the stock over time (this is called vesting). And when you vest stock the IRS treats it like income and it gets added to your W2 as such.
The 83(b) election allows you to take the entire tax hit immediately even though you don't have the ownership rights on the stock yet. You need to come up with the tax payment but since you "own" the stock even when it vests you won't pay additional taxes, and your ownership starts the clock on long term gains (vs short term gains).
If the stock is going up an 83b can save you some money, if it is going down it makes it more complicated (you can write off up to $3,000 of "loss" per year of stock which is worth less than the 83b election price. I got to do that for just over 10 years on my dot com era 83b stock election.
Generally places like Facebook or Google will sell some of your RSUs as they vest to cover the tax hit so its pretty invisible to you.