I had to dig thru the Fannie Mae and Freddie Mac guidelines for asset-based mortgages (that's the search term you need). Best I could figure out was "Take 70% of the balance of the portfolio ACCOUNT, divide into 36, and that's the amount of income that account can support. Recognizing it might be down a few % between when I calculated and when they verify the balance, I added in a bit more safety margin. This got me over the hump.
Interesting. Can you explain this more?
Say I have an account with $100k in it. Its accepted value is $70k.
Is the 36 based on the old ~1/3 goes to rent/mortgage/etc. rule? So if the mortgage payment is $1100/month, $3055 "income" is needed? What kind of monthly payment does a $70k account support?
I have two accounts, FatMan with $100k in it and LittleBoy with $50k.
70% of $100K = $70k. $70k / 36 months = $1944.44. This is the maximum income per month that the FatMan account is considered able to support for a 30 year mortgage. LittleBoy can only handle half that, or $972.22 per month. These two accounts can support $2916.66 per month. However, FatMan is NOT considered capable of $2916.66 per month, with the expectation that you would then switch to LittleBoy when FatMan has been consumed.
Note that we're talking about a 15 or 30 year mortgage. Obviously, something is wrong with the math I just described, which is best described as a lack of common sense. The concept of the 4% rule fell on deaf ears. So, as in many things to do with a mortgage, there are rules and there is common sense, and the consumer of the mortgage violates common sense at their peril.
Note that in my case, my portfolio was not worth ANY income until I set up a recurring income draw upon it. They want to see the recurring income hit your checking account before it is useable by their formula for how much income the account will support. Normal policy for a US mortgage is to show the last 2 statements for an account. So, ideally I would have ALREADY set up that income stream well before I went shopping for a mortgage, early enough to show the mortgage lender 2 statements showing that income.
The fact that I had been living without such a draw and paying all my bills also fell on deaf ears. In my case, I was starting SS in January. My SS award letter was sufficient for allowing that SS income to count. My SS annual award that was starting up was $3k shy of my annual new mortgage PITA cost. Didn't matter. I'm sitting on ~$1.5M in portfolio value and none of that portfolio would count as income until those recurring income payments hit my account.
Here's what I did to get past that. On 1-Jan I had pulled out the RMD of $14k plus an extra $6k (for $20K) out of one account. I was going to use it to pay off a HELOC I had been using for a couple months to cover renovation expenses. This particular account was an inherited IRA that was serviced by a financial advisor I had met in person years ago. (My dad had died and my mom introduced us at his office.) So I set up a recurring payment of $18k every six months and had the advisor send the mortgage lender a letter that said the $20k was part of a $36k recurring draw (with an extra $2k this time) that was paid out every six months. I actually set up the recurring withdrawal so it wasn't technically a lie (even though the January money had been pulled out prior to me setting up a recurring payment. (I hadn't read the Fannie Mae and Freddie Mac guidelines yet, so I didn't know better then.)
Note that until I could show them that the first payment hit my checking account it still DIDN'T COUNT as income.
Unless I actually happen to need $18K when the next withdrawal I'll cancel it and revert to a "send me money on a one-off basis when I tell you to."
I hope that I made clear what I did and what was required of me. If you understood that but are left thinking, "But that makes no financial sense..." then rest assured you've probably got this info down pat.
So, my best advice is to get all the money you are willing to use as a down payment in your checking account, set up recurring payments using the guidelines above, preferably from a taxable account so you can put unused money back into it later, and wait until you've got 2 statements showing all that. You'll have a much easier time of it.
Plus, if you've got business dealings going on with irregular income or payments, do that business in a different checking account. Otherwise, like me, you'll have to write up explanations of them. It's a pain in the butt.
Oh, if you want to know, but "how much income do I need for a $200k mortgage?", I really couldn't tell you. Sorry.