diff --git a/R/tailor.R b/R/tailor.R
index 5186e33..7678acd 100644
--- a/R/tailor.R
+++ b/R/tailor.R
@@ -167,6 +167,9 @@ fit.tailor <- function(object, .data, outcome, estimate, probabilities = c(),
   if (any(c("probability", "everything") %in%
           purrr::map_chr(object$adjustments, purrr::pluck, "inputs"))) {
     check_selection(enquo(probabilities), columns$probabilities, "probabilities")
+    for (col in columns$probabilities) {
+      check_variable_type(.data[[col]], "probability", "probabilities")
+    }
   }
 
   .data <- .data[, names(.data) %in% unlist(columns)]
@@ -177,6 +180,9 @@ fit.tailor <- function(object, .data, outcome, estimate, probabilities = c(),
 
   object <- set_tailor_type(object, .data[[columns$outcome]])
 
+  check_variable_type(.data[[columns$outcome]], object$type, "outcome")
+  check_variable_type(.data[[columns$estimate]], object$type, "estimate")
+
   object <- new_tailor(
     object$type,
     adjustments = object$adjustments,
@@ -210,7 +216,7 @@ predict.tailor <- function(object, new_data, ...) {
 
 set_tailor_type <- function(object, y, call = caller_env()) {
   if (object$type != "unknown") {
-    check_outcome_type(y, object$type, call = call)
+    check_variable_type(y, object$type, "outcome", call = call)
     return(object)
   }
   if (is.factor(y)) {
diff --git a/R/utils.R b/R/utils.R
index 38ce547..378f30e 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -343,22 +343,26 @@ check_method <- function(method,
   method
 }
 
-# at `fit()` time, we check the type of the outcome vs the type
+# at `fit()` time, we check the type of inputted variables vs the type
 # supported by the applied adjustments. where this is called currently,
 # we know already that `type` is not "unknown"
-check_outcome_type <- function(outcome, type, call) {
-  outcome_is_compatible <-
+check_variable_type <- function(variable, type, description, call = caller_env()) {
+  if (identical(type, "unknown")) {
+    return()
+  }
+
+  is_compatible <-
     switch(
       type,
-      regression = is.numeric(outcome),
-      binary = , multiclass = is.factor(outcome),
+      probability = , regression = is.numeric(variable),
+      binary = , multiclass = is.factor(variable),
       FALSE
     )
 
-  if (!outcome_is_compatible) {
+  if (!is_compatible) {
     cli_abort(
       "Tailors with {type} adjustments are not compatible
-       with {.cls {class(outcome)}} outcomes.",
+       with a {.cls {class(variable)}} {.arg {description}}.",
       call = call
     )
   }
diff --git a/tests/testthat/_snaps/utils.md b/tests/testthat/_snaps/utils.md
index 7f78056..dd88c5c 100644
--- a/tests/testthat/_snaps/utils.md
+++ b/tests/testthat/_snaps/utils.md
@@ -45,7 +45,7 @@
         test_numeric), estimate = c(predicted), probabilities = c(Class1, Class2))
     Condition
       Error in `fit()`:
-      ! Tailors with binary adjustments are not compatible with <numeric> outcomes.
+      ! Tailors with binary adjustments are not compatible with a <numeric> `outcome`.
 
 ---
 
@@ -54,7 +54,7 @@
       outcome = c(truth), estimate = c(Class1))
     Condition
       Error in `fit()`:
-      ! Tailors with regression adjustments are not compatible with <factor> outcomes.
+      ! Tailors with regression adjustments are not compatible with a <factor> `outcome`.
 
 ---
 
@@ -63,7 +63,7 @@
         test_date), estimate = c(predicted), probabilities = c(Class1, Class2))
     Condition
       Error in `fit()`:
-      ! Tailors with binary adjustments are not compatible with <POSIXct/POSIXt> outcomes.
+      ! Tailors with binary adjustments are not compatible with a <POSIXct/POSIXt> `outcome`.
 
 ---
 
@@ -74,6 +74,51 @@
       Error in `fit()`:
       ! Only factor and numeric outcomes are currently supported.
 
+# fit.tailor() errors informatively with incompatible estimate
+
+    Code
+      fit(tailor() %>% adjust_probability_threshold(0.1), two_class_example, outcome = c(
+        predicted), estimate = c(test_numeric), probabilities = c(Class1, Class2))
+    Condition
+      Error in `fit()`:
+      ! Tailors with binary adjustments are not compatible with a <numeric> `estimate`.
+
+---
+
+    Code
+      fit(tailor() %>% adjust_numeric_range(lower_limit = 0.1), two_class_example,
+      outcome = c(Class1), estimate = c(truth))
+    Condition
+      Error in `fit()`:
+      ! Tailors with regression adjustments are not compatible with a <factor> `estimate`.
+
+---
+
+    Code
+      fit(tailor() %>% adjust_probability_threshold(0.1), two_class_example, outcome = c(
+        truth), estimate = c(test_date), probabilities = c(Class1, Class2))
+    Condition
+      Error in `fit()`:
+      ! Tailors with binary adjustments are not compatible with a <POSIXct/POSIXt> `estimate`.
+
+---
+
+    Code
+      fit(tailor() %>% adjust_predictions_custom(hey = "there"), two_class_example,
+      outcome = c(truth), estimate = c(test_date), probabilities = c(Class1))
+    Condition
+      Error in `fit()`:
+      ! Tailors with binary adjustments are not compatible with a <POSIXct/POSIXt> `estimate`.
+
+# fit.tailor() errors informatively with incompatible probability
+
+    Code
+      fit(tailor() %>% adjust_probability_threshold(0.1), two_class_example, outcome = c(
+        truth), estimate = c(predicted), probabilities = c(test_date))
+    Condition
+      Error in `fit()`:
+      ! Tailors with probability adjustments are not compatible with a <POSIXct/POSIXt> `probabilities`.
+
 # find_tune_id() works
 
     Code
diff --git a/tests/testthat/test-utils.R b/tests/testthat/test-utils.R
index f8a405c..49daa50 100644
--- a/tests/testthat/test-utils.R
+++ b/tests/testthat/test-utils.R
@@ -166,6 +166,80 @@ test_that("fit.tailor() errors informatively with incompatible outcome", {
   )
 })
 
+test_that("fit.tailor() errors informatively with incompatible estimate", {
+  skip_if_not_installed("modeldata")
+  library(modeldata)
+
+  two_class_example$test_numeric <- two_class_example$Class1 + 1
+  two_class_example$test_date <- as.POSIXct(two_class_example$Class1)
+
+  # supply a numeric estimate to a binary tailor
+  expect_snapshot(
+    error = TRUE,
+    fit(
+      tailor() %>% adjust_probability_threshold(.1),
+      two_class_example,
+      outcome = c(predicted),
+      estimate = c(test_numeric),
+      probabilities = c(Class1, Class2)
+    )
+  )
+
+  # supply a factor estimate to a regression tailor
+  expect_snapshot(
+    error = TRUE,
+    fit(
+      tailor() %>% adjust_numeric_range(lower_limit = .1),
+      two_class_example,
+      outcome = c(Class1),
+      estimate = c(truth)
+    )
+  )
+
+  # supply a totally wild estimate to a regression tailor
+  expect_snapshot(
+    error = TRUE,
+    fit(
+      tailor() %>% adjust_probability_threshold(.1),
+      two_class_example,
+      outcome = c(truth),
+      estimate = c(test_date),
+      probabilities = c(Class1, Class2)
+    )
+  )
+
+  # supply a totally wild estimate to an unknown tailor
+  expect_snapshot(
+    error = TRUE,
+    fit(
+      tailor() %>% adjust_predictions_custom(hey = "there"),
+      two_class_example,
+      outcome = c(truth),
+      estimate = c(test_date),
+      probabilities = c(Class1)
+    )
+  )
+})
+
+test_that("fit.tailor() errors informatively with incompatible probability", {
+  skip_if_not_installed("modeldata")
+  library(modeldata)
+
+  two_class_example$test_date <- as.POSIXct(two_class_example$Class1)
+
+  # supply a date probability to a binary tailor
+  expect_snapshot(
+    error = TRUE,
+    fit(
+      tailor() %>% adjust_probability_threshold(.1),
+      two_class_example,
+      outcome = c(truth),
+      estimate = c(predicted),
+      probabilities = c(test_date)
+    )
+  )
+})
+
 test_that("find_tune_id() works", {
   # empty input
   expect_equal(find_tune_id(list()), NA_character_)