The code that defines how the fact graph works is here: https://github.com/IRS-Public/direct-file/tree/main/direct-file/fact-graph-scala https://github.com/IRS-

The code that defines how the fact graph works is here: https://github.com/IRS-Public/direct-file/tree/main/direct-file/fact-graph-scala https://github.com/IRS-Public/direct-file/tree/main/direct-f... but the actual tax definitions that deal with facts and derived calculation are here: https://github.com/IRS-Public/direct-file/tree/main/direct-file/backend/src/main/resources/tax https://github.com/IRS-Public/direct-file/tree/main/direct-f... See for example the standard deduction and tax rate calculations https://github.com/IRS-Public/direct-file/blob/main/direct-file/backend/src/main/resources/tax/standardDeduction.xml https://github.com/IRS-Public/direct-file/blob/main/direct-f... https://github.com/IRS-Public/direct-file/blob/main/direct-file/backend/src/main/resources/tax/taxCalculations.xml https://github.com/IRS-Public/direct-file/blob/main/direct-f... I imagine these are based on the MeF (Modernized e-File) schemas because the system needs to transform the input data into XML MeF schemas to submit electronically to the MeF system (See https://www.irs.gov/e-file-providers/modernized-e-file-mef-schemas-and-business-rules https://www.irs.gov/e-file-providers/modernized-e-file-mef-s...)