Tax in Purchase Order

Question

Hi,
In City of San Diego, the Non Deductable tax is required to be calculated on certain condition types and certain condition types do not attract the taxes.
Example
Suppose the pricing of material is as follows.
a.     Gross Price PBXX - $100.00
b.     Discount before tax %age (ZTDP) u2013 1% = $1.00
c.     Taxable Fuel Surcharge (ZTFS) - $10.00
d.     Hazardous Material fee - $10.00
In the example above the sum of a, b & c is taxable and d is non taxable.
Thus the total PO value should be calculated as below
Taxable Amount = $100-$1+$10 = $109.00. This value should be considered as the base value for condition BASB in tax schema TAXUSJ.
Tax say 7.775% = $8.45
Non Taxable Amount = $10.00
Total PO Amount would be = $109.00$8.45$10.00 = $127.45
The calculation schema is created according to this requirement (please refer the attachment). However, as per standard SAP, the tax is always calculated on the total of all the conditions.
So, in above example as per standard SAP tax would be calculated on $119.00 instead of $109.00
We have tried following options to address this issue
Option 1: Mark Non taxable conditions as Statistical in the calculation schema.
Issues with this optionu2013 This works fine as purchase order. However, as these conditions are statistical, the value of these conditions are not considered in net value calculation. Due to this the value of these conditions is not getting encumbered. This being public sector, the total PO price needs to get encumbered.
Option 2: Treat these conditions as some kind tax and create them with the tax category as u201CTaxu201D instead of Discount or Surcharges
Issue with this option: Though we knew that this is really not a best option we tried this. However, the values of these conditions do not get encumbered.
Option 3: Pass on subtotal of taxable amount to KOMP-KZWI6. Then in tax calculation schema TAXUSJ, maintain the routine 21 (KZWI6) for Alternate Formula for Condition Base value for condition type BASB (Base Amount).
The routine 21 is as follows
Pricing procedure subtotal 6
form frm_kond_basis_021.
  xkwert = komp-kzwi6.
endform.
Though this should have been worked correctly, it is not working. System still calculates taxes on Total of all condition types
Option 4: Pass on subtotal amount to KOMP-KZWI6 and use BAdi EXTENSION_US_TAXES Method ME_TAXCOM_MEPO. The details of this BAdi are as enclosed with the message.
This logic is to route the program to a subtotal from KZWI6 instead of NETWR so that taxes are calculated only on the subtotal. This subtotal is carried over to field KOMP-KZWI6. System then picks up this subtotal and considers this as BASE amount in tax calculation schema for the calculation of tax.
Issue with this option: Though it works perfectly fine with single line PO, it does not work for multi line PO. At the time of PO creation, it calculates the taxes correctly. However, during saving of the PO, it changes the taxes. The taxes after saving are totally different and sometimes randomly calculated. The behavior is un-predictable. However, sometimes it works correctly. In some cases, it changes the tax amounts randomly (tax amount of line 1 will be shown to line 10 and that of line 10 will be shown in line 8).
The details of Calculation Schema and Tax Schema are as enclosed with this message.
Calculation Schema
1     1     ZPB0     CoSD Gross Price     0     0          9
1     2     PBXX     Gross Price     0     0          9
3     1     ZTDQ     Discount Bf Tax Qty     1     0     b
3     2     ZTDV     Discount Bf Tax Valu     1     0     b
3     3     ZTDP     Discount Bf Tax %age     1     0     b
4     1     ZTFV     Txbl Value Freight     1     0     b
4     2     ZTFQ     Txbl Qty Freight     1     0     b
4     3     ZTFP     Txbl %age freight     1     0     b
5     0     ZTFS     Txbl Fuel Surcharge     1     0     b
20     0          Net value incl. disc.     1     5          6
21     1     NAVS     Non-Deductible Tax     0     0     b
21     2     NAVM     Non-Deductible Tax     0     0     b
22     0          Net value incl. tax     20     21
25     1     ZNDQ     Discount Af Tax Qty     1     0     b
25     2     ZNDV     Discount Af Tax Valu     1     0     b
25     3     ZNDP     Discount Af Tax %age     1     0     b
26     1     ZCTQ     CA Tire Fee Qty     1     0     b
26     2     ZCTV     CA Tire Fee Value     1     0     b
31     1     ZNFV     N Txbl Value Freight     1     0     b
31     2     ZNFQ     N Txbl Qty Freight     1     0     b
31     3     ZNFP     N Txbl %age freight     1     0     b
32     1     ZNFS     N Txbl Fuel Surcharg     1     0     b
33     0     ZHMF     Hazardous Matl Fee     0     0     b
34     0     ZMSC     Misc Fee Value     0     0     b
35     1     SKTO     Cash Discount     1     0
40     0          Actual price     22     39          S
60     0     WOTB     OTB Procurement     0     0
70     0     GRWR     Statistical Value     20     0
75     0     GWLB     Stat. Val. LB-Comp.     0     0
79     0          Border crossing value     70     78          C
Tax Schema TAXUSJ
100     0     BASB     Base Amount     0     0               0     0     0
120     0          Subtotal     0     0               0   0     0
200     0          Distributed to G/L     100     110               0     0     0
210     0     JP1I     A/P Sales Tax 1 Inv.     120     0               00     0     NVV
220     0     JP2I     A/P Sales Tax 2 Inv.     120     0               0     0     0     NVV
230     0     JP3I     A/P Sales Tax 3 Inv.     120     0               0     0     0     NVV
240     0     JP4I     A/P Sales Tax 4 Inv.     120     0               0     0     0     NVV
300     0          Expensed     0     0               0     0     0
310     0     JP1E     A/P Sales Tax 1 Exp.     120     0               0     0     0     VS1
320     0     JP2E     A/P Sales Tax 2 Exp.     120     0               0     0     0     VS2
330     0     JP3E     A/P Sales Tax 3 Exp.     120     0               0     0     0     VS3
340     0     JP4E     A/P Sales Tax 4 Exp.     120     0               0     0     0     VS4
400     0          Self-assessment     0     0               0     0     0
410     0     JP1U     A/P Sales Tax 1 Use     210     0               0     0     0     MW1
420     0     JP2U     A/P Sales Tax 2 Use     220     0               0     0     0     MW2
430     0     JP3U     A/P Sales Tax 3 Use     230     0               0     0     0     MW3
440     0     JP4U     A/P Sales Tax 4 Use     240     0               0     0     0     MW4
500     0          Accrued     0     0               0     0     0
510     0     JR1     A/R Sales Tax 1     120     0               0     0     0     MW1
520     0     JR2     A/R Sales Tax 2     120     0               0     0     0     MW2
530     0     JR3     A/R Sales Tax 3     120     0               0     0     0     MW3
540     0     JR4     A/R Sales Tax 4     120     0               0     0     0     MW4

Answer 1

Hello,
         can u make it more simple & understandable i.e in 8-10 lines.
u have written a lot & much confusing way.
JP