Not enough time, too many projects. Useful projects I did over the weekend with Opus 4.6 and GPT 5.4 (just casually chatting with it).
2025 Taxes
Dumped all pdfs of all my tax forms into a single folder, asked Claude the rename them nicely. Ask it to use Gemini 2.5 Flash to extract out all tax-relevant details from all statements / tax forms. Had it put together a webui showing all income, deductions, etc, for the year. Had it estimate my 2025 tax refund / underpay.
Result was amazing. I now actually fully understand the tax position. It broke down all the progressive tax brackets, added notes for all the extra federal and state taxes (i.e. Medicare, CA Mental Health tax, etc).
Finally had Claude prepare all of my docs for upload to my accountant: FinCEN reporting, summary of all docs, etc.
Desk Fabrication
Planning on having a furniture maker fabricate a custom walnut solid desk for a custom office standing desk. Want to create a STEP of the exact cuts / bevels / countersinks / etc to help with fabrication.
Worked with Codex to plan out and then build an interactive in-browser 3D CAD experience. I can ask Codex to add some component (i.e. a grommet) and it will generate a parameterized B-rep geometry for that feature and then allow me to control the parameters live in the web UI.
Codex found Open CASCADE Technology (OCCT) B-rep modeling library, which has a web assembly compiled version, and integrated it.
Now have a WebGL view of the desk, can add various components, change their parameters, and see the impact live in 3D.
I love the tax use case.
What scares me though is how I've (still) seen ChatGPT make up numbers in some specific scenarios.
I have a ChatGPT project with all of my bloodwork and a bunch of medical info from the past 10 years uploaded. I think it's more context than ChatGPT can handle at once. When I ask it basic things like "Compare how my lipids have trended over the past 2 years" it will sometimes make up numbers for tests, or it will mix up the dates on a certain data points.
It's usually very small errors that I don't notice until I really study what it's telling me.
And also the opposite problem: A couple days ago I thought I saw an error (when really ChatGPT was right). So I said "No, that number is wrong, find the error" and instead of pushing back and telling me the number was right, it admitted to the error (there was no error) and made up a reason why it was wrong.
Hallucinations have gotten way better compared to a couple years ago, but at least ChatGPT seems to still break down especially when it's overloaded with a ton of context, in my experience.
In my case, what I like to do is extract data into machine-readable format and then once the data is appropriately modeled, further actions can use programmatic means to analyze. As an example, I also used Claude Code on my taxes:
1. I keep all my accounts in accounting software (originally Wave, then beancount)
2. Because the machinery is all in programmatically queriable means, the data is not in token-space, only the schema and logic
I then use tax software to prep my professional and personal returns. The LLM acts as a validator, and ensures I've done my accounts right. I have `jmap` pull my mail via IMAP, my Mercury account via a read-only transactions-only token and then I let it compare against my beancount records to make sure I've accounted for things correctly.
For the most part, you want it to be handling very little arithmetic in token-space though the SOTA models can do it pretty flawlessly. I did notice that they would occasionally make arithmetic errors in numerical comparison, but when using them as an assistant you're not using them directly but as a hypothesis generator and a checker tool and if you ask it to write out the reasoning it's pretty damned good.
For me Opus 4.6 in Claude Code was remarkable for this use-case. These days, I just run `,cc accounts` and then look at the newly added accounts in fava and compare with Mercury. This is one of those tedious-to-enter trivial-to-verify use-cases that they excel at.
To be honest, I was fine using Wave, but without machine-access it's software that's dead to me.
I've gotten better results by telling it "write a Python program to calculate X"
For the tax thing. I had Claude write a CLI and a prompt for Gemini Flash 2.5 to do the structured extraction: i.e. .pdf -> JSON. The JSON schema was pretty flexible, and open to interpretation by Gemini, so it didn't produce 100% consistent JSON structures.
To then "aggregate" all of the json outputs, I had Claude look at the json outputs, and then iterate on a Python tool to programmatically do it. I saw it iterating a few times on this: write the most naive Python tool, run it, throws exception, rinse and repeat, until it was able to parse all the json files sensibly.
Yeah, in my user prompt I have "Whenever you are asked to perform any operation which could be done deterministically by a program, you should write a program to do it that way and feed it the data, rather than thinking through the problem on your own." It's worked wonders.
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Good call. I’ve also had better results pre-processing PDFs, extracting data into structured format, and then running prompts against that.
Which should pair well with the “write a script” tactic.
Yeah, asking for a tool to do a thing is almost always better than asking for the thing directly, I find. LLMs are kind of not there in terms of always being correct with large batches of data. And when you ask for a script, you can actually verify what's going on in there, without taking leaps of faith.
I’d say for these use cases it’s better to make it build the tools that do the thing than to make it doing the thing itself.
And it usually takes just as long.
I don't know, but I would never upload such sensitive information to a service like that (local models FTW!) or trust the numbers.
Which part is sensitive? Social is public, income is private but what is someone going to do with it?
It's not good in some job negotiations if someone has a very clear picture of what your current net worth and income is. Also in some purchases companies could price discriminate more effectively against you.
Now that's a question I'd feel more confident having answered by an LLM. Personally, I'm tired of arguing with "nothing to hide", which (no offense) is just terribly naive these days.
> Result was amazing. I now actually fully understand the tax position.
You couldn’t do that with TurboTax or block’s tax file? You don’t have to submit or pay.
Be careful with taxes. Hallucinations will cost you.
I had ai hallucinate that you can use different container images at runtime for emr serverless. That was incorrect its only at application creation time.
Hope you dont get audited
> had Claude prepare all of my docs for upload to my accountant: FinCEN reporting, summary of all docs, etc.
I imagine your accountant had the same reaction I do when an amateur shows me their vibe codebase.