OK perhaps i should have included more information. I am working at home for myself, no employees. I work fora company that does not take out taxes. I sent 1000 in april. I missed the july deadline, but i will be sending $5000 this week> I will talk to an accountant this wee.
I may check into it after things start turning back around.
Get an accountant. Now, if you get a good one, you can ask him to show you what to do, and then after a couple years, assuming your business stays about the same, you can do it yourself.
Same with even just an itemized 1040 Taxpayer. At least get your 1st year done by a Pro.
1040A and 1040EZ- you should be able to do that yourselves.
No, you don’t have to do this. You can pay less, if that’s what your Estimate comes out to, that’s why they are called Estimated Tax Payments.
This (paying estimated taxes) is a maybe. Depending on what the other income is. No penalty will be assessed if the total tax liability is less than $1000. So, if she can claim herself as a deduction, she might have no income tax and only owe $300-$400 in SE Taxes. If she can write a check for $300 with no pain later when she’s not working, then it’s no so bad.
But yes, seeing a live Tax Pro is a good idea.
Now, by “accountant” I mean a real Tax Pro- a CPA or an Enrolled Agent.
Q about sending money in periodically: Wouldn’t it make more sense to figure out what you should owe, invest it (like in a CD), collect the interest, and then pay at the end of the year?
Business taxes are due quarterly, I believe, not annually like personal taxes.
That MIGHT be OK your first year, and it’s OK if you owe less than $1000. Otherwise, you might have to pay a Estimated Tax Penalty.
Besides, a Money Market is paying less than 1% now.
Good. You won’t regret it.
ETA: Talk to the accountant BEFORE you send the money.
Personal taxes also can (and should) be paid quarterly if you are not deducting enough on your W4.
When I worked in one state and lived in another at a corporate job (that is, not self-employed) I paid state taxes quarterly because the idiots in Payroll couldn’t comprehend how to make the withholding work, and after hearing horror stories from other people who worked/lived across the state line I said to hell with it, I’m not paying a penalty because some biddy is stubbornly ignorant. Most people don’t take the option, but you are able to do that.
I’m pretty sure the money a good accountant could save would be ample to pay his fees as well as putting extra dough in the OP’s pocket.
So (to the OP) GET AN ACCOUNTANT!
I’m astonished that no one has suggested that already. 
What follows is a quotation of the entire OP–every word of it:
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If you are a sole proprietor, they are the same. Business tax = personal tax. The taxes are listed under your name & SSN (or in my case, my husband’s, since we’re married).
Your post read:
This is ambigous - you make no reference to the original salary, but instead imply that an accountant costs $40,000 a year.
This is why you should hire an accountant!