Use ChatGPT to Speed Up Complex Income Analysis

For Mortgage Underwriters · Updated September 3, 2026

of 4· Use ChatGPT to clarify your analysis method before you start

What you'll accomplish

Complex income analysis gets faster when AI handles the structure and you handle the numbers. This guide builds a ChatGPT workflow for organizing your analysis plan, checking your methodology, summarizing findings for the file, and drafting clear explanations for LOs and borrowers. while keeping you in control of the actual calculation.

What you'll need

ChatGPT account at chatgpt.com (free tier works; Plus recommended for Custom Instructions)
Income documentation for the file you're working on (you'll extract numbers manually)
IMPORTANT: Never paste actual borrower PII (name, SSN, DOB) into ChatGPT. work with anonymized figures only
Cost: Free

Step 1: Use ChatGPT to clarify your analysis method before you start

Before diving into a complex income type, confirm your methodology with ChatGPT:

Open chatgpt.com and start a new conversation
Ask your methodology question:

Copy and paste this

I'm underwriting a conventional loan for a borrower who is a 40% owner of an S-corp. They receive both W-2 wages from the business and show K-1 income. What is the Fannie Mae method for calculating qualifying income? Which forms do I need, what add-backs are allowed, and how do I handle income that's declining year-over-year?

Read the methodology explanation before starting your analysis
Ask follow-up questions: "What if the S-corp has a loss in Year 2 but income in Year 1?"

Step 2: Use ChatGPT to build your calculation structure

For complex income types, ask ChatGPT to help you structure the calculation in a logical sequence:

Copy and paste this

Walk me through the step-by-step calculation sequence for Schedule C self-employed income using the FNMA method. I'll collect the numbers from the tax returns — just give me the structure in order.

What you get: A numbered calculation sequence:

Start with Net Profit from Schedule C Line 31
Add back Depreciation from Form 4562
Add back Depletion (if applicable)
Add back Business Use of Home (Schedule C Line 30)
Subtract non-recurring income

Step 3: Summarize your completed analysis for the file

After you've done the calculations yourself (using your spreadsheet), use ChatGPT to generate the file documentation:

Enter your completed numbers (no borrower name or SSN. just the figures and employment type):

Copy and paste this

Write an income analysis summary for a file note. Employment type: self-employed sole proprietor, Schedule C. Year 1 net profit: $68,400. Add-backs: depreciation $4,200, business mileage $1,800. Adjusted Year 1: $74,400. Year 2 net profit: $72,600. Add-backs: depreciation $3,900. Adjusted Year 2: $76,500. Two-year average: $75,450. Monthly qualifying income: $6,288. Income is stable/increasing. Per FNMA B3-3.4.

Use the output as your Encompass file note or income calculation summary

Step 4: Draft an explanation for the LO

When your income calculation produces a number different from what the LO expected:

Copy and paste this

Write a plain-English explanation for a loan officer explaining why a borrower's qualifying income is $6,288/month despite having gross Schedule C receipts that appear higher. Explain: depreciation add-back increases qualifying income vs. what the Schedule C net shows, but overall qualifying is lower than gross receipts because we use net income methodology. No jargon. Keep it under 150 words.

Tools:ChatGPT