I'm reviewing loan files and I have just encountered my first irregular payment stream, resulting from Mortgage Insurance premiums. As a result, I'm having difficulty arriving at the APR disclosed on the TIL.

The payment stream is something like this:
120 monthly payments varying from $1113.99 to $1165.98
3 monthly payments of $1112.11
236 payments of $1101.90
1 payment of $1101.73

How do I enter this first variable payment stream in to the APR program to test it? I can't get anywhere close to the disclosed APR at the moment and don't want to report a tolerance issue if there is not one.

Anyone?
I have an e-mail in the the OCC's APRWIN help, but I'm finishing up fieldwork today and could really use some guidance on how to resolve the issue.

I hear you and we've been there. Someone said to average that first payment stream: low/figure + hi/figure DIV/2= average payment. Sound logical? I do wonder how often logic works..
This is also higher tolerance percentage because the payment streams are many.

This can be a tricky calculation - I've never gotten it to the penny, but have gotten close. The premium is based on an average of the declining balance of the base loan amount (loan amount without MIP).

HUD's premium calculation instructions can be found here - http://www.hud.gov/offices/hsg/comp/premiums/sfpcalc.cfm

In most cases, the MIP will cease once the loan reaches 78% LTV.

You have to know the amortization schedule of the loan to have orginally calculated the TIL. So, you must have the payment stream somewhere. You can't test the APR without it or by estimating average payments. If you are using the OCC APR calculator, you have to enter each one of the payment streams.

Exactly right. Since FHA loans have annually decreasing premiums, your disclosable payment schedule that looks like this:
120 monthly payments varying from $1113.99 to $1165.98
3 monthly payments of $1112.11
236 payments of $1101.90
1 payment of $1101.73
must be entered into APRWIN like this:
12 @ 1165.98
12 @ [next lower premium amount + P&I]
12 @ [next lower premium amount + P&I]
12 @ [next lower premium amount + P&I]
12 @ [next lower premium amount + P&I]
12 @ [next lower premium amount + P&I]
12 @ [next lower premium amount + P&I]
12 @ [next lower premium amount + P&I]
12 @ [next lower premium amount + P&I]
12 @ 1113.99
3 @ 1112.11
236 @ 1101.90
1 @ 1101.73

If your records do not contain all of the MI premium amounts in effect in years 2 - 9 (or the full payments for those years) you do not have evidence of compliance and are violating Section 226.25 of Regulation Z.