diff --git a/runatlantis.io/docs/api-endpoints.md b/runatlantis.io/docs/api-endpoints.md
index ce622979da..b1f5d463c2 100644
--- a/runatlantis.io/docs/api-endpoints.md
+++ b/runatlantis.io/docs/api-endpoints.md
@@ -28,6 +28,8 @@ Execute [atlantis plan](using-atlantis.md#atlantis-plan) on the specified reposi
 | Type       | string  | Yes      | Type of the VCS provider (Github/Gitlab) |
 | Paths      | Path    | Yes      | Paths to the projects to run the plan    |
 | PR         | int     | No       | Pull Request number                      |
+| BaseBranch | string  | No       | The branch where the PR will be merged   |
+| Commit     | string  | No       | The commit to checkout in the PR         |
 
 #### Path
 
diff --git a/server/controllers/api_controller.go b/server/controllers/api_controller.go
index ff85371469..d0d9d5b94f 100644
--- a/server/controllers/api_controller.go
+++ b/server/controllers/api_controller.go
@@ -39,6 +39,8 @@ type APIRequest struct {
 	Repository string `validate:"required"`
 	Ref        string `validate:"required"`
 	Type       string `validate:"required"`
+	Commit     string
+	BaseBranch string
 	PR         int
 	Projects   []string
 	Paths      []struct {
@@ -167,6 +169,13 @@ func (a *APIController) apiPlan(request *APIRequest, ctx *command.Context) (*com
 	return &command.Result{ProjectResults: projectResults}, nil
 }
 
+func GetOrElse(val, def string) string {
+	if val != "" {
+		return val
+	}
+	return def
+}
+
 func (a *APIController) apiApply(request *APIRequest, ctx *command.Context) (*command.Result, error) {
 	cmds, cc, err := request.getCommands(ctx, a.ProjectCommandBuilder.BuildApplyCommands)
 	if err != nil {
@@ -233,13 +242,16 @@ func (a *APIController) apiParseAndValidate(r *http.Request) (*APIRequest, *comm
 		return nil, nil, http.StatusForbidden, fmt.Errorf("repo not allowlisted")
 	}
 
+	baseBranch := GetOrElse(request.BaseBranch, request.Ref)
+	headCommit := GetOrElse(request.Commit, request.Ref)
+
 	return &request, &command.Context{
 		HeadRepo: baseRepo,
 		Pull: models.PullRequest{
 			Num:        request.PR,
-			BaseBranch: request.Ref,
+			BaseBranch: baseBranch,
 			HeadBranch: request.Ref,
-			HeadCommit: request.Ref,
+			HeadCommit: headCommit,
 			BaseRepo:   baseRepo,
 		},
 		Scope: a.Scope,
diff --git a/server/controllers/api_controller_test.go b/server/controllers/api_controller_test.go
index 3b3aa520aa..9877e7b909 100644
--- a/server/controllers/api_controller_test.go
+++ b/server/controllers/api_controller_test.go
@@ -24,11 +24,22 @@ const atlantisTokenHeader = "X-Atlantis-Token"
 const atlantisToken = "token"
 
 func TestAPIController_Plan(t *testing.T) {
+	testPlan(t, "main", "", "")
+}
+
+func TestAPIController_PlanWithNewParams(t *testing.T) {
+	testPlan(t, "my-feature-branch", "HEAD", "main")
+}
+
+func testPlan(t *testing.T, ref, commit, baseBranch string) {
 	ac, projectCommandBuilder, projectCommandRunner := setup(t)
 	body, _ := json.Marshal(controllers.APIRequest{
 		Repository: "Repo",
-		Ref:        "main",
+		Ref:        ref,
 		Type:       "Gitlab",
+		Commit:     commit,
+		BaseBranch: baseBranch,
+		PR:         100,
 		Projects:   []string{"default"},
 	})
 	req, _ := http.NewRequest("POST", "", bytes.NewBuffer(body))
@@ -36,7 +47,28 @@ func TestAPIController_Plan(t *testing.T) {
 	w := httptest.NewRecorder()
 	ac.Plan(w, req)
 	ResponseContains(t, w, http.StatusOK, "")
-	projectCommandBuilder.VerifyWasCalledOnce().BuildPlanCommands(Any[*command.Context](), Any[*events.CommentCommand]())
+
+	headCommit := controllers.GetOrElse(commit, ref)
+	baseBranch = controllers.GetOrElse(baseBranch, ref)
+
+	repo := models.Repo{}
+	cmdContext := &command.Context{
+		HeadRepo: repo,
+		Pull: models.PullRequest{
+			Num:        100,
+			BaseBranch: baseBranch,
+			HeadBranch: ref,
+			HeadCommit: headCommit,
+			BaseRepo:   repo,
+		},
+		Scope: ac.Scope,
+		Log:   ac.Logger,
+	}
+	commentCmd := &events.CommentCommand{
+		ProjectName: "default",
+	}
+
+	projectCommandBuilder.VerifyWasCalledOnce().BuildPlanCommands(cmdContext, commentCmd)
 	projectCommandRunner.VerifyWasCalledOnce().Plan(Any[command.ProjectContext]())
 }