Do we continue to pay estimated taxes?

That will depend upon how large those investments were, the type, and her Social Security benefits. Without hard numbers, it's not possible to give concrete advice.

Assuming that he was self-employed, she won't need to make estimated payments based upon that now non-existent income, but there may be other reasons that she needs to.

Depends on the size of the investments she cashed in. If under around $10,000 total for the year, no she doesn't need to. Even if a bit more, no need, she can just pay at tax time if she owes. If over 15 or 20K, she probably should.

assuming you filed your parents' final return as married filing jointly

your mother now in 2012 is filed as single, she is allowed $3800 personal exemption and $5950 standard deduction, plus $1400 if she is over 65

half of her SS added to all her other income amounting to $25000 or more some of her SS will be taxable

if she will anticipate $1000 owing income tax she will need to file 1040ES

depending on her incomes, she can have her

taxes withdraw from check.

as for estimated taxes by dad = no need to

continue.