(I looked for similar cases and answers and could not find anything, so please forgive me if it was)
I have a 1099 contract with a client for services in the finance industry. Because of my 30+ years of professional IT services, he also asked me to do a variety of IT-related services for him already before he hired me for the financial services. In the past, these were rather small things (e.g., setting up a newsletter), and he always paid my invoices promptly without question. Sometimes we would agree on an amount upfront and mostly we did not - he trusted me, and I trusted him.
This month, he asked me to simplify an Excel sheet with a large number of columns which was very difficult for him to navigate. I created a proof of concept for him which he again paid promptly. We reviewed the POC together to verify that I was going in the direction he wanted. When he confirmed that, I said that finalizing this app (which it turned out to be) will be a lot more work. He said that's fine and did not ask any further questions. Since we saw each other almost every day, I kept him in the loop about me working on the app, that I spent a significant amount of time already, and that there is a lot more to do. He always responded with "that's fine".
In fact, he liked what I had done as POC so much that he said later that he had reached out to the patent office for filing copyright. There was never any agreement on transfer of intellectual property.
Last Thursday I sent him another invoice since we had reached a milestone close to completion. He said this invoice was too high, and that he would not pay it. He would be willing to pay "what's fair" but not this. And he wanted me to adust the invoice to a lower amount.
Sidenote: since he did not make any attempt from his end to reach any kind of resolution I ended the working relationship this Monday. He now claims that he does not owe me anything.
If I remove his access to the app (it's a Google file) does he then have the right to not pay the invoice and I have waived my right to receive payment?
Is the transfer of intellectual property automatically assumed? Is there any way for me to veto his copyright registration?
Thank you very much in advance for any input.