The IRS wants quarterly estimated tax payments based on an estimate of what the business will make that year. They want you to pay 100% of the previous year's tax over the course of 4 quarters or 90% of the current year's estimated income. However, since this is their first year in business and they've only been operational for a few months it's possible to have your "under payment penalty" waived since it's their first year. Their tax professional should be able to apply the waiver. Best

You mentioned that you have a newly incorporated Startup, and an incorporated Consulting Business how are they incorporated? As an S-Corp or a C-Corp? If they are S corp then none of that matters because because of the businesses activities will flow through on your personal tax return anyway. If it is C-Corp then you could look at the transfer of assets if you wanted to keep the books clean. Also depending on the type of equipment you have, some of them may have a useful life of 5-7 years. You should first find out how they are incorporated, if S-Corp then it's best to do nothing in my opinion, because it won't change anything.

I agree with Naeem. Do some research in companies that you believe in, and invest in them. Invest directly or through good growth stock mutual funds. A gradual increase in your saved money every year will start generate that passive income that people talk about. The stock market's average since inception has been around 11.5%. For example, if you were to have $500k saved up, and you are earning 11.5% annually that could yield $57,500 (500k x .115) which would be considered passive income.