diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..939e149
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,48 @@
+{
+  "nodes": {
+    "home-manager": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1751500614,
+        "narHash": "sha256-mYiYNsTJkbQouC5YHOTgqVpjpELoNf9f4z5ZeY4NfPg=",
+        "owner": "nix-community",
+        "repo": "home-manager",
+        "rev": "a5b56720841121d2189c011e445c4be4c943bab5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "home-manager",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1751271578,
+        "narHash": "sha256-P/SQmKDu06x8yv7i0s8bvnnuJYkxVGBWLWHaU+tt4YY=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "3016b4b15d13f3089db8a41ef937b13a9e33a8df",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "home-manager": "home-manager",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..15228c1
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,250 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    home-manager.url = "github:nix-community/home-manager";
+    home-manager.inputs.nixpkgs.follows = "nixpkgs";
+  };
+
+  outputs = {
+    self,
+    nixpkgs,
+    home-manager,
+  }: let
+    system = "x86_64-linux";
+    pkgs = import nixpkgs {inherit system;};
+
+    pyproject = builtins.fromTOML (builtins.readFile ./pyproject.toml);
+    inherit (pyproject) project;
+
+    taskcheck = pkgs.python3Packages.buildPythonApplication {
+      pname = project.name;
+      inherit (project) version;
+      pyproject = true;
+      src = ./.;
+      nativeBuildInputs = with pkgs.python3Packages; [setuptools];
+
+      dependencies = with pkgs.python3Packages; [
+        appdirs
+        icalendar
+        random-unicode-emoji
+        requests
+        rich
+      ];
+    };
+    random-unicode-emoji = pkgs.python3Packages.buildPythonPackage rec {
+      pname = "random-unicode-emoji";
+
+      version = "2.9";
+
+      pyproject = true;
+
+      nativeBuildInputs = with pkgs.python3Packages; [setuptools];
+
+      src = pkgs.fetchFromGitHub {
+        owner = "NicPWNs";
+        repo = "random-unicode-emoji-py";
+        rev = version;
+        hash = "sha256-8BfwcZSzQpq1jJuvavIrW84rDvLfKdXr6TLXP8echM4=";
+      };
+    };
+  in {
+    packages.${system}.default = taskcheck;
+    homeManagerModules.default = {
+      config,
+      lib,
+      pkgs,
+      ...
+    }: let
+      inherit (lib) mkOption mkEnableOption mkIf mkMerge;
+
+      cfg = config.programs.taskcheck;
+
+      toml = pkgs.formats.toml {};
+    in {
+      options = {
+        programs.taskcheck = {
+          enable = mkEnableOption "taskcheck";
+
+          optional_hm_config = mkEnableOption "Set Optional HM Configurations";
+
+          package = mkOption {
+            default = taskcheck;
+          };
+
+          settings = mkOption {
+            default = {
+              time_maps = {
+                work = {
+                  monday = [[9 12.30] [14 17]];
+                  tuesday = [[9 12.30] [14 17]];
+                  wednesday = [[9 12.30] [14 17]];
+                  thursday = [[9 12.30] [14 17]];
+                  friday = [[9 12.30] [14 17]];
+                };
+              };
+              scheduler = {
+                days_ahead = 365;
+                weight_urgency = 1.0;
+              };
+              report = {
+                include_unplanned = true;
+                additional_attributes = [];
+                additional_attributes_unplanned = [];
+                # emoji_keywords = {};
+              };
+              calendars = {
+                holidays = {
+                  url = "https://www.officeholidays.com/ics-clean/usa/nebraska";
+                  event_all_day_is_blocking = true;
+                  expiration = 720; # In hours (720 hours = 30 days)
+                };
+              };
+            };
+            inherit (toml) type;
+          };
+        };
+      };
+
+      config = mkIf cfg.enable {
+        home.packages = mkIf (cfg.package != null) [cfg.package];
+        programs.taskwarrior.enable = true;
+        programs.taskwarrior.config = mkMerge [
+          {
+            uda = {
+              time_map = {
+                type = "string";
+                label = "Time Map";
+                default = "work";
+              };
+              estimated.type = "duration";
+              estimated.label = "Estimated Time";
+              completion_date.type = "date";
+              completion_date.label = "Expected Completion Date";
+              scheduling.type = "string";
+              scheduling.label = "Scheduling";
+              min_block = {
+                type = "numeric";
+                label = "Minimum Time Block";
+                default = "2";
+              };
+            };
+            recurrence.confirmation = "no";
+          }
+          (mkIf
+            cfg.optional_hm_config {
+              urgency = {
+                uda.estimated = {
+                  PT1H.coefficient = 1;
+                  PT2H.coefficient = 2.32;
+                  PT3H.coefficient = 3.67;
+                  PT4H.coefficient = 4.64;
+                  PT5H.coefficient = 5.39;
+                  PT6H.coefficient = 6.02;
+                  PT7H.coefficient = 6.56;
+                  PT8H.coefficient = 7.03;
+                  PT9H.coefficient = 7.45;
+                  PT10H.coefficient = 7.82;
+                  PT11H.coefficient = 8.16;
+                  PT12H.coefficient = 8.47;
+                  PT13H.coefficient = 8.75;
+                  PT14H.coefficient = 9.01;
+                  PT15H.coefficient = 9.25;
+                  PT16H.coefficient = 9.47;
+                  PT17H.coefficient = 9.68;
+                  PT18H.coefficient = 9.87;
+                  PT19H.coefficient = 10.05;
+                  PT20H.coefficient = 10.22;
+                  PT21H.coefficient = 10.38;
+                  PT22H.coefficient = 10.53;
+                  PT23H.coefficient = 10.67;
+                  P1D.coefficient = 10.80;
+                  P1DT1H.coefficient = 10.93;
+                  P1DT2H.coefficient = 11.05;
+                  P1DT3H.coefficient = 11.16;
+                  P1DT4H.coefficient = 11.27;
+                  P1DT5H.coefficient = 11.37;
+                  P1DT6H.coefficient = 11.47;
+                  P1DT7H.coefficient = 11.56;
+                  P1DT8H.coefficient = 11.65;
+                  P1DT9H.coefficient = 11.73;
+                  P1DT10H.coefficient = 11.81;
+                  P1DT11H.coefficient = 11.89;
+                  P1DT12H.coefficient = 11.96;
+                };
+                "inherit" = 1;
+                blocked.coefficient = 0;
+                blocking.coefficient = 0;
+                waiting.coefficient = 0;
+                scheduled.coefficient = 0;
+              };
+              report.ready.columns = [
+                "id"
+                "start.age"
+                "entry.age"
+                "depends.indicator"
+                "priority"
+                "project"
+                "tags"
+                "recur.indicator"
+                "scheduled.relative"
+                "due.relative"
+                "until.remaining"
+                "description"
+                "urgency"
+              ];
+              journal.info = 0;
+            })
+        ];
+        xdg.configFile."task/taskcheck.toml".source = toml.generate "taskcheck.toml" cfg.settings;
+      };
+    };
+    checks.x86_64-linux = {
+      moduleTest = pkgs.testers.runNixOSTest {
+        name = "moduleTest";
+
+        nodes.machine1 = {
+          imports = [home-manager.nixosModules.home-manager];
+
+          users.users.alice = {
+            isNormalUser = true;
+          };
+
+          home-manager.users.alice = _:
+          # { config, ... }: # config is home-manager's config, not the OS one
+          {
+            imports = [self.homeManagerModules.default];
+            home.stateVersion = "24.05";
+
+            programs.taskcheck = {
+              enable = true;
+              optional_hm_config = true;
+            };
+          };
+        };
+
+        testScript = ''
+          machine.wait_for_unit("default.target")
+
+          assert machine.execute("su - alice bash -c 'task add estimated:2h time_map:work project:docs Write Documentation'")[0] == 0
+          assert machine.execute("su - alice bash -c 'task add estimated:1h time_map:work project:dev due:eom Code review meeting'")[0] == 0
+          assert machine.execute("su - alice bash -c 'task add estimated:3h time_map:personal project:hobby Personal Project'")[0] == 0
+          assert machine.execute("su - alice bash -c 'task 1'")[0] == 0
+
+          assert machine.execute("su - alice bash -c 'taskcheck'")[0] == 0
+
+          assert machine.execute("su - alice bash -c 'ls -lath ~/.config/task/'")[0] == 0
+
+          print("taskcheck.toml:\n", machine.execute("su - alice bash -c 'cat ~/.config/task/taskcheck.toml'")[1])
+
+          print("taskrc:\n", machine.execute("su - alice bash -c 'cat ~/.config/task/home-manager-taskrc'")[1])
+
+          print("task report:\n", machine.execute("su - alice bash -c 'taskcheck -r 1w'")[1])
+
+          # TODO: setup nameserver to resolve calendar host
+          # print("task report:\n", machine.execute("su - alice bash -c 'taskcheck --schedule && taskcheck -r 1w'")[1])
+
+        '';
+      };
+    };
+  };
+}