Well I’m not looking for 100% accuracy, and it doesn’t need to cover all types of income. I’m interested in long term investment income with various input types

Well I’m not looking for 100% accuracy, and it doesn’t need to cover all types of income. I’m interested in long term investment income with various input types of accounts and investments given different inflation and tax policy scenarios. It just needs to be better than the software I’ve seen which is basically trash (assumes a flat percent tax).