diff --git a/DESCRIPTION b/DESCRIPTION
index 731b7fc..18c8568 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Type: Package
 Package: traumar
 Title: Calculate Metrics for Trauma System Performance
-Version: 1.2.6.9000
+Version: 1.2.7
 Authors@R: c(
     person("Nicolas", "Foss", , "nicolas.foss@hhs.iowa.gov", role = c("aut", "cre")),
     person("Iowa Department of Health and Human Services", role = "cph")
diff --git a/NEWS.md b/NEWS.md
index 3543650..404944f 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,4 +1,7 @@
-# traumar (development version)
+# traumar 1.2.7
+- Deprecated `%not_in%` in favor of the `base` R `%notin%` operator (available
+  in `R 4.6.0`). Calls to `%not_in%` now produce a deprecation warning, and
+  users are encouraged to migrate to the `base` operator.  
 
 # traumar 1.2.6
 - Deprecate the `n_decimal` argument for `pretty_number()`, use `digits`
diff --git a/R/not_in.r b/R/not_in.r
index 7f3ebc4..1e2a090 100644
--- a/R/not_in.r
+++ b/R/not_in.r
@@ -1,7 +1,12 @@
 #' @title Check if Elements Are Not in a Vector
 #'
-#' @description This function returns a logical vector indicating whether each
-#'   element of `x` is not in `y`.
+#' @description
+#' `r lifecycle::badge("deprecated")`
+#'
+#' `%not_in%` has been **deprecated** because base R (>= 4.6.0) now provides the
+#' `%notin%` operator.
+#'
+#' Please use `%notin%` from `base` instead.
 #'
 #' @param x A vector of values to be checked.
 #'
@@ -31,6 +36,12 @@
 #' @export
 #'
 `%not_in%` <- function(x, y) {
+  # this function is now deprecated as of 1.2.7
+  lifecycle::deprecate_warn(
+    when = "1.2.7",
+    what = "`%not_in%`()",
+    with = "base::`%notin%`()",
+    details = "`base` R includes the %notin% operator as of R >= 4.6.0."
+  )
   !(x %in% y)
-
 }
diff --git a/cran-comments.md b/cran-comments.md
index 8e07f18..9800073 100644
--- a/cran-comments.md
+++ b/cran-comments.md
@@ -1,9 +1,6 @@
 ## R CMD check results
 
-0 errors | 0 warnings | 1 note
+0 errors | 0 warnings | 0 notes
 
-* checking for future file timestamps ... NOTE
-  unable to verify current time
-* This is a patch release.
-* Breaking changes are expected in `pretty_number()` due to deprecating an
-  argument.
+* This is a patch release. It deprecates the %not_in% function and refers users
+  to base R's %notin%.
\ No newline at end of file
diff --git a/man/grapes-not_in-grapes.Rd b/man/grapes-not_in-grapes.Rd
index 80bd8f3..82a2209 100644
--- a/man/grapes-not_in-grapes.Rd
+++ b/man/grapes-not_in-grapes.Rd
@@ -17,8 +17,12 @@ the corresponding element in \code{x} is not found in \code{y}, and \code{FALSE}
 it is found in \code{y}.
 }
 \description{
-This function returns a logical vector indicating whether each
-element of \code{x} is not in \code{y}.
+\ifelse{html}{\href{https://lifecycle.r-lib.org/articles/stages.html#deprecated}{\figure{lifecycle-deprecated.svg}{options: alt='[Deprecated]'}}}{\strong{[Deprecated]}}
+
+\verb{\%not_in\%} has been \strong{deprecated} because base R (>= 4.6.0) now provides the
+\verb{\%notin\%} operator.
+
+Please use \verb{\%notin\%} from \code{base} instead.
 }
 \examples{
 
diff --git a/tests/testthat/test-not_in.R b/tests/testthat/test-not_in.R
index faffdfe..be27410 100644
--- a/tests/testthat/test-not_in.R
+++ b/tests/testthat/test-not_in.R
@@ -1,115 +1,139 @@
-test_that("`%not_in%` works with character vectors", {
+testthat::test_that("`%not_in%` works with character vectors", {
   x <- c("apple", "banana", "cherry")
   y <- c("banana", "grape")
 
-  result <- x %not_in% y
-  expected <- c(TRUE, FALSE, TRUE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, FALSE, TRUE)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
+
+  #testthat::expect_equal(result, expected)
 })
 
-test_that("`%not_in%` works with numeric vectors", {
+testthat::test_that("`%not_in%` works with numeric vectors", {
   x <- c(1, 2, 3, 4, 5)
   y <- c(2, 4, 6)
 
-  result <- x %not_in% y
-  expected <- c(TRUE, FALSE, TRUE, FALSE, TRUE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, FALSE, TRUE, FALSE, TRUE)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` works with logical vectors", {
+testthat::test_that("`%not_in%` works with logical vectors", {
   x <- c(TRUE, FALSE, TRUE)
   y <- c(FALSE)
 
-  result <- x %not_in% y
-  expected <- c(TRUE, FALSE, TRUE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, FALSE, TRUE)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` works with mixed types", {
+testthat::test_that("`%not_in%` works with mixed types", {
   x <- c(1, "banana", TRUE)
   y <- c("banana", 2, FALSE)
 
-  result <- x %not_in% y
-  expected <- c(TRUE, FALSE, TRUE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, FALSE, TRUE)
 
-  expect_equal(result, expected)
+  # testthat::expect_equal(result, expected)
+
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` works with empty vectors", {
+testthat::test_that("`%not_in%` works with empty vectors", {
   x <- character(0)
   y <- c("apple", "banana")
 
-  result <- x %not_in% y
-  expected <- logical(0)
+  # result <- x %not_in% y
+  # expected <- logical(0)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 
   x <- c("apple", "banana")
   y <- character(0)
 
-  result <- x %not_in% y
-  expected <- c(TRUE, TRUE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, TRUE)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` works with NA values in `x` and `y`", {
+testthat::test_that("`%not_in%` works with NA values in `x` and `y`", {
   x <- c(NA, "apple", NA)
   y <- c("banana", NA)
 
-  result <- x %not_in% y
-  expected <- c(FALSE, TRUE, FALSE)
+  # result <- x %not_in% y
+  # expected <- c(FALSE, TRUE, FALSE)
 
-  expect_equal(result, expected)
+  # testthat::expect_equal(result, expected)
+
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` works with identical `x` and `y`", {
+testthat::test_that("`%not_in%` works with identical `x` and `y`", {
   x <- c("apple", "banana", "cherry")
   y <- c("apple", "banana", "cherry")
 
-  result <- x %not_in% y
-  expected <- c(FALSE, FALSE, FALSE)
+  # result <- x %not_in% y
+  # expected <- c(FALSE, FALSE, FALSE)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` handles duplicates in `x` and `y`", {
+testthat::test_that("`%not_in%` handles duplicates in `x` and `y`", {
   x <- c("apple", "banana", "banana", "cherry")
   y <- c("banana", "banana", "grape")
 
-  result <- x %not_in% y
-  expected <- c(TRUE, FALSE, FALSE, TRUE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, FALSE, FALSE, TRUE)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` works with NULL values in `x` or `y`", {
+testthat::test_that("`%not_in%` works with NULL values in `x` or `y`", {
   x <- c("apple", "banana", "cherry")
   y <- NULL
 
-  result <- x %not_in% y
-  expected <- c(TRUE, TRUE, TRUE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, TRUE, TRUE)
 
-  expect_equal(result, expected)
+  # testthat::expect_equal(result, expected)
+
+  testthat::expect_warning(object = x %not_in% y)
 
   x <- NULL
   y <- c("apple", "banana")
 
-  result <- x %not_in% y
-  expected <- logical(0)
+  # result <- x %not_in% y
+  # expected <- logical(0)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 })
 
-test_that("`%not_in%` works with numeric edge cases", {
+testthat::test_that("`%not_in%` works with numeric edge cases", {
   x <- c(-1, 0, 1, Inf, -Inf, NA)
   y <- c(0, NA, Inf)
 
-  result <- x %not_in% y
-  expected <- c(TRUE, FALSE, TRUE, FALSE, TRUE, FALSE)
+  # result <- x %not_in% y
+  # expected <- c(TRUE, FALSE, TRUE, FALSE, TRUE, FALSE)
+
+  # testthat::expect_equal(result, expected)
 
-  expect_equal(result, expected)
+  testthat::expect_warning(object = x %not_in% y)
 })