From 0156968e3714378326a9016e280512b4f97ee530 Mon Sep 17 00:00:00 2001
From: Robert Sesek <rsesek@bluestatic.org>
Date: Sun, 20 Sep 2020 13:43:45 -0400
Subject: [PATCH] Add the fed2020 overlay.

The 2020 tax return forms are likely to be quite similar to the 2019
versions, with inflation-adjustments to constant values. To avoid
copy-paste-tweak with the forms, use an overlay: forms with differences
from the previous year can be rewritten, but unchanged ones should just
use the prior year's form.

Constant values are now associated with an overlay TaxReturn class, so
the inflation adjustments do not require new forms.
---
 src/fed2020/Form1040.test.ts | 24 +++++++++
 src/fed2020/TaxReturn.ts     | 98 ++++++++++++++++++++++++++++++++++++
 src/fed2020/index.ts         |  8 +++
 3 files changed, 130 insertions(+)
 create mode 100644 src/fed2020/Form1040.test.ts
 create mode 100644 src/fed2020/TaxReturn.ts
 create mode 100644 src/fed2020/index.ts

diff --git a/src/fed2020/Form1040.test.ts b/src/fed2020/Form1040.test.ts
new file mode 100644
index 0000000..76f37b1
--- /dev/null
+++ b/src/fed2020/Form1040.test.ts
@@ -0,0 +1,24 @@
+// Copyright 2020 Blue Static <https://www.bluestatic.org>
+// This program is free software licensed under the GNU General Public License,
+// version 3.0. The full text of the license can be found in LICENSE.txt.
+// SPDX-License-Identifier: GPL-3.0-only
+
+import { Person } from '../core';
+import { NotFoundError } from '../core/Errors';
+
+import { Form1040, FilingStatus } from '.';
+import TaxReturn from './TaxReturn';
+
+test('standard deduction', () => {
+  const filingStatusToResult = {
+    [FilingStatus.MarriedFilingJoint]: 24800,
+    [FilingStatus.Single]: 12400,
+    [FilingStatus.MarriedFilingSeparate]: 12400,
+  };
+
+  for (const filingStatus of Object.values(FilingStatus)) {
+    const tr = new TaxReturn();
+    const f = new Form1040({ filingStatus });
+    expect(f.getValue(tr, '9')).toBe(filingStatusToResult[filingStatus]);
+  }
+});
diff --git a/src/fed2020/TaxReturn.ts b/src/fed2020/TaxReturn.ts
new file mode 100644
index 0000000..681bbd8
--- /dev/null
+++ b/src/fed2020/TaxReturn.ts
@@ -0,0 +1,98 @@
+// Copyright 2020 Blue Static <https://www.bluestatic.org>
+// This program is free software licensed under the GNU General Public License,
+// version 3.0. The full text of the license can be found in LICENSE.txt.
+// SPDX-License-Identifier: GPL-3.0-only
+
+import { default as TaxReturn2019, Constants as Constants2019 } from '../fed2019/TaxReturn';
+
+import { FilingStatus } from '.';
+
+// The values are from RP-19-44: https://www.irs.gov/pub/irs-drop/rp-19-44.pdf.
+//
+// The double Object.assign is to work around
+// https://github.com/microsoft/TypeScript/issues/38516. Using the spread
+// operator directly into an object literal results in "error TS4029: Public
+// property 'constants' of exported class has or is using name 'FilingStatus'
+// from external module "ustaxlib/src/fed2019/TaxReturn" but cannot be named".
+export const Constants = Object.assign(Object.assign({}, Constants2019, {
+  taxBrackets: {
+    [FilingStatus.MarriedFilingJoint]: [
+      [ 19750, 0.10, 0 ],
+      [ 80250, 0.12, 1975 ],
+      [ 171050, 0.22, 9235 ],
+      [ 326600, 0.24, 29211 ],
+      [ 414700, 0.32, 66543 ],
+      [ 622050, 0.35, 94735 ],
+      [ Infinity, 0.37, 167307.50 ]
+    ],
+    [FilingStatus.Single]: [
+      [ 9875, 0.10, 0 ],
+      [ 40125, 0.12, 987.50 ],
+      [ 85525, 0.22, 4617.50 ],
+      [ 163300, 0.24, 14605.50 ],
+      [ 207350, 0.32, 33271.50 ],
+      [ 518400, 0.35, 47367.50 ],
+      [ Infinity, 0.37, 156235 ]
+    ],
+    [FilingStatus.MarriedFilingSeparate]: [
+      [ 9875, 0.10, 0 ],
+      [ 40125, 0.12, 987.50 ],
+      [ 85525, 0.22, 4617.50 ],
+      [ 163300, 0.24, 14605.50 ],
+      [ 207350, 0.32, 33271.50 ],
+      [ 311025, 0.35, 47367.50 ],
+      [ Infinity, 0.37, 83653.75 ]
+    ],
+  },
+
+  standardDeduction: {
+    [FilingStatus.MarriedFilingJoint]: 24800,
+    [FilingStatus.Single]: 12400,
+    [FilingStatus.MarriedFilingSeparate]: 12400,
+  },
+
+  capitalGains: {
+    rate0MaxIncome: {
+      [FilingStatus.MarriedFilingJoint]: 80000,
+      [FilingStatus.Single]: 40000,
+      [FilingStatus.MarriedFilingSeparate]: 40000,
+    },
+    rate15MaxIncome: {
+      [FilingStatus.MarriedFilingJoint]: 496600,
+      [FilingStatus.MarriedFilingSeparate]: 441450,
+      [FilingStatus.Single]: 441450,
+    },
+  },
+
+  qualifiedBusinessIncomeDeductionThreshold: {
+    [FilingStatus.MarriedFilingJoint]: 326600,
+    [FilingStatus.MarriedFilingSeparate]: 163300,
+    [FilingStatus.Single]: 163300,
+  },
+
+  amt: {
+    exemption: {
+      [FilingStatus.MarriedFilingJoint]: 113400,
+      [FilingStatus.Single]: 72900,
+      [FilingStatus.MarriedFilingSeparate]: 56700,
+    },
+    phaseout: {
+      [FilingStatus.MarriedFilingJoint]: 1036800,
+      [FilingStatus.Single]: 518400,
+      [FilingStatus.MarriedFilingSeparate]: 518400,
+    },
+    limitForRate28Percent: {
+      [FilingStatus.MarriedFilingJoint]: 197900,
+      [FilingStatus.Single]: 197900,
+      [FilingStatus.MarriedFilingSeparate]: 98950,
+    },
+  },
+
+  prevYearStandardDeduction: Constants2019.standardDeduction,
+}));
+
+export default class TaxReturn extends TaxReturn2019 {
+  readonly constants = Constants;
+
+  get year() { return 2020; }
+}
diff --git a/src/fed2020/index.ts b/src/fed2020/index.ts
new file mode 100644
index 0000000..2c7f1b3
--- /dev/null
+++ b/src/fed2020/index.ts
@@ -0,0 +1,8 @@
+// Copyright 2020 Blue Static <https://www.bluestatic.org>
+// This program is free software licensed under the GNU General Public License,
+// version 3.0. The full text of the license can be found in LICENSE.txt.
+// SPDX-License-Identifier: GPL-3.0-only
+
+export * from '../fed2019';
+
+export { default as TaxReturn } from './TaxReturn';
-- 
2.22.5