I'm the owner of a small business (sole proprietorship) and make quarterly estimated taxes. My estimates were made on my assumptions at the beginning of the year which recently changed. Specifically, I've decided to bunch up donations to a Donor Advised Fund for this year (my spouse and I itemize based on SLT and mortgage interest) for a sizeable amount, which may lower our tax bill by a 5-figure amount.
Effectively, it would also mean I'm paid up on my 2024 estimated taxes through Q3. Do I have an obligation to make a Q4 payment or can I elect to pay $0 in Q4? How should I handle potential overpayments of estimated taxes?
Estimates are optional to pay. You can skip it. You will enter all payments made into your return when you file and will get credit for them just like withholding.
As an addendum, if you overpay with your estimated tax payments, any over payment will be refunded to you at tax filing time. I've been self-employed for 20 years and I intentionally always overpay my estimated taxes - or at least a try to. That practically guarantees me a refund of the overpaid amount each year. Though I have had 2-3 years where I ended up owing a bit more than what I paid in quarterly taxes, I was still well within underpay limits so I didn't incur an underpayment penalty.
I had a refund once and still had a penalty for not paying in evenly during the year.
Just a guess based on no facts, but maybe that penalty was because you didn't do that option where you can break down quarterly earnings?
I had something similar to that a few years ago, and I think it was you @VolvoGirl that told me about do that. When I did it, that eliminated the $18 penalty I would have otherwise been assessed.