diff --git a/NEWS.md b/NEWS.md
index 6f436f17..284042a6 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,11 @@
 # cardx 0.2.1.9008
 
+* Implemented `summary(extend=TRUE)` in `ard_survival_survfit()` to return results for time points out of bounds. (#224)
+
+* Added a `data.frame` method to `ard_survival_survfit()`.
+
+* Added a warning for incorrect formula type to `ard_survival_survfit()`. (#223)
+
 # cardx 0.2.1
 
 ## New Features and Updates
diff --git a/R/ard_survival_survfit.R b/R/ard_survival_survfit.R
index 461e1773..02d2dd44 100644
--- a/R/ard_survival_survfit.R
+++ b/R/ard_survival_survfit.R
@@ -34,28 +34,23 @@
 #' @inheritParams rlang::args_dots_empty
 #'
 #' @section Formula Specification:
+#' When passing a [`survival::survfit()`] object to `ard_survival_survfit()`,
+#' the `survfit()` call must use an evaluated formula and not a stored formula.
+#' Including a proper formula in the call allows the function to accurately
+#' identify all variables included in the estimation. See below for examples:
 #'
-#' The `x` argument can accepts a [survival::survfit()] object, which must be created from a formula or previously
-#' fitted model. In order to identify the underlying variable names when processing this formula, it must be supplied
-#' directly to [survival::survfit()] rather and not taken from a variable. For example, `x` can be constructed and
-#' supplied to `ard_survival_survfit()` as follows:
-#' ```{r, eval = FALSE}
-#' data <- mtcars
-#' x <- survival::survfit(survival::Surv(mpg, am) ~ cyl, data = data)
-#'
-#' ard_survival_survfit(x, times = 25)
-#' ```
+#' ```r
+#' library(cardx)
+#' library(survival)
 #'
-#' Alternatively, a data frame can be passed as `x`, with the formula outcome supplied to `y` and stratification
-#' variables passed to `variables`, and the formula will be constructed and passed to [survival::survfit()] within the
-#' function.
-#' ```{r, eval = FALSE}
-#' x <- mtcars
-#' y <- "survival::Surv(mpg, am)"
-#' variables <- "cyl"
+#' # include formula in `survfit()` call
+#' survfit(Surv(time, status) ~ sex, lung) |> ard_survival_survfit(time = 500)
 #'
-#' ard_survival_survfit(x, y, variables, times = 25)
+#' # you can also pass a data frame to `ard_survival_survfit()` as well.
+#' lung |>
+#'   ard_survival_survfit(y = Surv(time, status), variables = "sex", time = 500)
 #' ```
+#' You **cannot**, however, pass a stored formula, e.g. `survfit(my_formula, lung)`
 #'
 #' @return an ARD data frame of class 'card'
 #' @name ard_survival_survfit
diff --git a/man/ard_survival_survfit.Rd b/man/ard_survival_survfit.Rd
index 93e4988e..0d68a851 100644
--- a/man/ard_survival_survfit.Rd
+++ b/man/ard_survival_survfit.Rd
@@ -70,28 +70,23 @@ survival fit model.
 }
 \section{Formula Specification}{
 
+When passing a \code{\link[survival:survfit]{survival::survfit()}} object to \code{ard_survival_survfit()},
+the \code{survfit()} call must use an evaluated formula and not a stored formula.
+Including a proper formula in the call allows the function to accurately
+identify all variables included in the estimation. See below for examples:
 
-The \code{x} argument can accepts a \code{\link[survival:survfit]{survival::survfit()}} object, which must be created from a formula or previously
-fitted model. In order to identify the underlying variable names when processing this formula, it must be supplied
-directly to \code{\link[survival:survfit]{survival::survfit()}} rather and not taken from a variable. For example, \code{x} can be constructed and
-supplied to \code{ard_survival_survfit()} as follows:
+\if{html}{\out{<div class="sourceCode r">}}\preformatted{library(cardx)
+library(survival)
 
-\if{html}{\out{<div class="sourceCode r">}}\preformatted{data <- mtcars
-x <- survival::survfit(survival::Surv(mpg, am) ~ cyl, data = data)
+# include formula in `survfit()` call
+survfit(Surv(time, status) ~ sex, lung) |> ard_survival_survfit(time = 500)
 
-ard_survival_survfit(x, times = 25)
+# you can also pass a data frame to `ard_survival_survfit()` as well.
+lung |>
+  ard_survival_survfit(y = Surv(time, status), variables = "sex", time = 500)
 }\if{html}{\out{</div>}}
 
-Alternatively, a data frame can be passed as \code{x}, with the formula outcome supplied to \code{y} and stratification
-variables passed to \code{variables}, and the formula will be constructed and passed to \code{\link[survival:survfit]{survival::survfit()}} within the
-function.
-
-\if{html}{\out{<div class="sourceCode r">}}\preformatted{x <- mtcars
-y <- "survival::Surv(mpg, am)"
-variables <- "cyl"
-
-ard_survival_survfit(x, y, variables, times = 25)
-}\if{html}{\out{</div>}}
+You \strong{cannot}, however, pass a stored formula, e.g. \code{survfit(my_formula, lung)}
 }
 
 \examples{