Revised Gross Book Balance = When we are calculating Revised Gross Book Balance for the period 1 we are taking Gross Book Balance But When we are calculating Periods 2 onwards we are taking Revised Gross Book Balance + Principal Payment (initial)+PSA$
Formula for : Principal Payment (initial)= PPMT - rev GBB * Effective Interest Rate
Formula for (PPMT) used in Alteryx : PPMT = (([Revised Gross Book Balance]*[Effective Interest Rate])/(1-(POW(1+[Effective Interest Rate],(-1*[Remaining Periods])))) is depending upon Effective Interest Rate, Revised Gross Book Balance and Remaining Periods
Formula for : rev GBB * Effective Interest Rate = Revised Gross Book Balance * Effective Interest Rate+PSA$
Formula for: PSA$= if (Revised Gross Book Balance= Principal Payment (initial),0, Revised Gross Book Balance*PSA%)
Things need to calculate in Alteryx 1. Revised Gross Book Balance 2. Principal Payment (initial) 3. PPMT 4. rev GBB * Effective Interest Rate. 5.PSA$ These five items are interdependent on each other.
| Effective Interest Rate | Gross Book Balance | Revised Gross Book Balance | Period | rev GBB * Effective Interest Rate | Remaining Periods | PPMT | Principal Payment (initial) | PSA% | PSA ($) |
| 7.763260% | 1,458,452 | 1458452 | 1 | 113223.3927 | 13 | 182130.32 | (68907) | 0 | 0 |
| 7.763260% | 1,458,452 | 1389545 | 2 | 107873.9688 | 12 | 182130.32 | (74256) | 0 | 0 |
| 7.763260% | 1,458,452 | 1315288 | 3 | 102109.2553 | 11 | 182130.32 | (80021) | 0 | 0 |
| 7.763260% | 1,458,452 | 1235267 | 4 | 95897.01211 | 10 | 182130.32 | (86233) | 0 | 0 |
| 7.763260% | 1,458,452 | 1149034 | 5 | 89202.49632 | 9 | 182130.32 | (92928) | 0 | 0 |
| 7.763260% | 1,458,452 | 1056106 | 6 | 81988.26787 | 8 | 182130.32 | (100142) | 0 | 0 |
| 7.763260% | 1,458,452 | 955964 | 7 | 74213.98012 | 7 | 182130.32 | (107916) | 0 | 0 |
| 7.763260% | 1,458,452 | 848048 | 8 | 65836.15421 | 6 | 182130.32 | (116294) | 0 | 0 |
| 7.763260% | 1,458,452 | 731754 | 9 | 56807.93589 | 5 | 182130.32 | (125322) | 0 | 0 |
| 7.763260% | 1,458,452 | 606431 | 10 | 47078.83353 | 4 | 182130.32 | (135051) | 0 | 0 |
| 7.763260% | 1,458,452 | 471380 | 11 | 36594.43567 | 3 | 182130.32 | (145536) | 0 | 0 |
| 7.763260% | 1,458,452 | 325844 | 12 | 25296.10675 | 2 | 182130.32 | (156834) | 0 | 0 |
| 7.763260% | 1,458,452 | 169010 | 13 | 13120.65919 | 1 | 182130.32 | (169010) | 0 | 0 |
Please refer to the attached excel sheet that will help for better understanding.
Any help would be highly appreciated.