diff --git a/README.md b/README.md
index 58e80721..abb490f9 100644
--- a/README.md
+++ b/README.md
@@ -55,4 +55,4 @@ Results will change as the underlying models improve. A fundamental reason for a
 
 
 ## Citing the Cost-of-Capital-Calculator Model
-Cost-of-Capital-Calculator (Version 1.5.0)[Source code], https://github.com/PSLmodels/Cost-of-Capital-Calculator
+Cost-of-Capital-Calculator (Version 1.5.1)[Source code], https://github.com/PSLmodels/Cost-of-Capital-Calculator
diff --git a/ccc/__init__.py b/ccc/__init__.py
index 602315f4..3626db7f 100644
--- a/ccc/__init__.py
+++ b/ccc/__init__.py
@@ -6,4 +6,4 @@
 from ccc.data import *
 from ccc.calculator import *
 
-__version__ = "1.5.0"
+__version__ = "1.5.1"
diff --git a/docs/book/content/intro.md b/docs/book/content/intro.md
index 3e381d1e..67db21e5 100644
--- a/docs/book/content/intro.md
+++ b/docs/book/content/intro.md
@@ -22,4 +22,4 @@ Results will change as the underlying models improve. A fundamental reason for a
 
 
 ## Citing the Cost-of-Capital-Calculator Model
-Cost-of-Capital-Calculator (Version 1.5.0)[Source code], https://github.com/PSLmodels/Cost-of-Capital-Calculator
\ No newline at end of file
+Cost-of-Capital-Calculator (Version 1.5.1)[Source code], https://github.com/PSLmodels/Cost-of-Capital-Calculator
\ No newline at end of file
diff --git a/environment.yml b/environment.yml
index d0e0d961..5fc6b490 100644
--- a/environment.yml
+++ b/environment.yml
@@ -3,7 +3,7 @@ channels:
 - conda-forge
 dependencies:
 - python
-- "taxcalc>=3.1.0"
+- "taxcalc>=4.0.0"
 - "paramtools>=0.18.3"
 - "pandas>=2.2.0"
 - bokeh>=3.1.1