sorry for your loss
your son's estate is entitled to the 3rd stimulus. The rule is that anyone who passed away after 12/31/20 who was eligible for the 3rd stimulus is entitled to it.
I would just respond to the IRS request to obtain another stimulus check and cash it. Explaining the situation may be a good idea.
if there was no income in 2021, why muddy the waters with filing a tax return? there is no requirement to file. My fear is if you file, you would have to answer that you didn't receive the 3rd stimulus, which creates a $1400 refund on the tax return and then when the IRS tries to process it, their records are going to show they already sent out the stimulus payment, they adjust the refund to zero and you are back to square one.
