I suspect I can build this in 6 to 10 hours, but it is always helpful to have another brain on the job. 3) There is an advanced function I would like to build, but sadly I can't recall the mathematical functions necessary to make the calculations. 

Helocs have many different ways to calculate income once you get outside of the bank world. 

I mainly want to ask if these assumptions are reasonable and if there's anything I haven't considered:(1) multifamily units in NJ close to New York City, ~$1,000,000, 20% down payment, (2) Using the following assumptions: 4% appreciation rate, 6.5% interest rate and 5.0% refinance after 5 years, $10,000 yearly maintenance fee(3) ~$6,000 monthly rental and assume 3% increase yearly with 5% vacancy rate(4) Based on the above, the calculated IRR if selling at the 10th year is ~19% (considering tax benefits) and ~17% (without tax benefits).

Remaining Balance: After the balloon payment, the remaining loan balance will be re-amortized over 5 years (60 months) at the same 6.5% interest rate.Payment TermsInitial Loan Terms (First 24 Months):The monthly payment for the first 24 months is based on a 12-year amortization schedule:Monthly Payment for First 24 Months: $1,573.39Remaining Balance at Month 24 (Prior to Balloon Payment):The balance after 24 months can be calculated using the amortization formula:Remaining Balance at Month 24: $157,113.92Balloon Payment:The balloon payment will be 50% of the remaining balance at Month 24:Balloon Payment Due at Month 24: $78,556.96Re-Amortization of Remaining Balance (After Balloon Payment):The remaining balance after the balloon payment will be:This amount will be re-amortized over 5 years (60 months) at the same 6.5% interest rate.Monthly Payment for Final 60 Months: $1,541.18Summary of Key Terms:• Purchase Price: $215,000• Down Payment: $43,000• Loan Amount: $172,000• Interest Rate: 6.5% (fixed)Initial Terms (First 24 Months):• Monthly Payment: $1,573.39• Balloon Payment Due at Month 24: $78,556.96Re-Amortized Terms (Final 60 Months):• Remaining Balance: $78,556.96• Monthly Payment: $1,541.18Additional Conditions:1.

However, I’m not sure how to accurately determine its value, given the configuration and the fact that it’s not fully rented.My Concerns:Determining Value: How should I calculate the fair market value for this type of property?

So your capital gain when you sell this property will be calculate against your tax basis and not against your mortgage as many investors expect.

- Suggest you Google "Amortization Calculator" and run a few scenarios to open your eyes!

Most lenders require 6-12 months from acquisition seasoning before using the appraised current fair market value to calculate LTV.

@Kevin Wood: Fixed Asset Management module is included in the QuickBooks Accountant version where you can calculate the depreciation.

It scales up to 37% once you get to around $12k of income but the UBIT is calculated after the first $1000 is deducted along with expenses and depreciation again only on the same % the property is mortgaged.