QAD 2017 Enterprise Edition > User Guides > Global Tax Management > Implementing GTM > Implementing Special Taxes > Custom Tax Calculation Methods
  
Custom Tax Calculation Methods
The transaction detail screen displays the following tax-related amounts for line items and trailer charges:
• Total line item or trailer charge amount
• Line item or trailer charge amount not subject to tax
• Line item or trailer charge amount that is subject to tax
• Total tax amount
• Recoverable and non-recoverable tax amounts
• For sales transactions, any tax your company absorbs rather than passes on to the customer
• For purchase transactions, any tax your company retains for direct payment to the government
To calculate tax amounts, GTM can use one of several standard calculation programs. Alternately, to resolve a localization issue, write a custom program. Specify a default program and override it as necessary for individual tax rates.
Standard GTM Tax Methods summarizes the differences among the tax calculation methods supplied with the system.

Standard GTM Tax Methods
 
Method
Program
Explanation
01
txmeth01.p
This generic method supports most taxes.
Tax Amount = Tax Rate * Item Amount
Note: For reverse-calculated taxes, Tax Amount = Tax Rate * [Item Amount / (1+Tax Rate)]
Taxable Base = Item Amount * Tax Base Percent
If Taxable Base < Min. Taxable, Tax Amount = Min. Taxable
If Taxable Base > Max. Taxable, Tax Amount = Max. Taxable
Recoverable Amount = Tax Amount * Recoverable Percent
02
txmeth02.p
Same as method 01 except that it supports luxury taxes and capped taxes that are assessed only on specific taxable base amounts.
If Taxable Base < Min. Taxable, Tax Amount = 0
If Taxable Base > Max. Taxable, Tax Amount = 0
03
txmeth03.p
Indicates you are importing tax amounts from an external system and do not want to recalculate them.
11
txmeth11.p
Same as method 01 but has a regressive calculation for reverse-calculated taxes.
Tax Amount = Tax Rate * Item Amount
20
txmeth20.p
Indicates that Quantum, through the Sales and Use Tax API, calculates taxes for each line item.
For custom programs, the file naming convention is txmeth##.p, where ## is the numeric identifier referenced in Tax Rate Maintenance. Use an identifier from 50 to 99; identifiers 00 through 49 are reserved for QAD use.
To implement the custom tax method, specify the identifier as the Tax Method in Tax Rate Maintenance (29.4.1). If the custom method is the default method for new tax rates, also specify it in Global Tax Management Control (29.24).
Set up a value in generalized codes for the new method so that it displays in the lookup on the Tax Method field in Tax Rate Maintenance.