diff --git a/conanfile.txt b/conanfile.txt
index e2763c275..703260a39 100644
--- a/conanfile.txt
+++ b/conanfile.txt
@@ -3,7 +3,6 @@ Poco/1.9.4@pocoproject/stable
 libsodium/1.0.18@bincrafters/stable
 boost/1.71.0@conan/stable
 gtest/1.8.1@bincrafters/stable
-mpfr/4.1.0
 
 [generators]
 cmake
diff --git a/src/cpp/lib/DecayRate.cpp b/src/cpp/lib/DecayRate.cpp
deleted file mode 100644
index 3e5603d21..000000000
--- a/src/cpp/lib/DecayRate.cpp
+++ /dev/null
@@ -1,49 +0,0 @@
-#include "DecayRate.h"
-
-#include <gmp.h>
-#include <mpfr.h>
-
-DecayRate::DecayRate()
-	: mDecayRate(0.0)
-{
-
-}
-
-DecayRate::~DecayRate()
-{
-
-}
-
-void DecayRate::calculateDecayRate(int daysPerYear/* = 356*/, Profiler* time/* = nullptr*/)
-{
-	
-	mpfr_t capital_n_log; mpfr_init(capital_n_log);
-	mpfr_t capital_0_log; mpfr_init(capital_0_log);
-	mpfr_t capital_diff; mpfr_init(capital_diff);
-	mpfr_t decay_rate_per_second; mpfr_init(decay_rate_per_second);
-	mpfr_t seconds_per_year;
-	mpfr_t days_per_year;
-	mpfr_init_set_ui(days_per_year, daysPerYear, MPFR_RNDN);
-	mpfr_init(seconds_per_year);
-	/*
-	typedef enum {
-	MPFR_RNDN=0,  // round to nearest, with ties to even 
-	MPFR_RNDZ,    // round toward zero 
-		MPFR_RNDU,    // round toward +Inf 
-		MPFR_RNDD,    // round toward -Inf 
-		MPFR_RNDA,    // round away from zero 
-		MPFR_RNDF,    // faithful rounding 
-		MPFR_RNDNA = -1 // round to nearest, with ties away from zero (mpfr_round) 
-} mpfr_rnd_t;
-
-	*/
-	//mpfr_rnd_t
-	// seconds per year = 60*60*24*daysPerYear
-	mpfr_mul_ui(seconds_per_year, days_per_year, 60 * 60 * 24, MPFR_RNDN);
-
-	mpfr_log_ui(capital_n_log, 50, MPFR_RNDN);
-	mpfr_log_ui(capital_0_log, 100, MPFR_RNDN);
-	mpfr_sub(capital_diff, capital_n_log, capital_0_log, MPFR_RNDN);
-	mpfr_div(decay_rate_per_second, capital_diff, seconds_per_year, MPFR_RNDN);
-	mDecayRate = mpfr_get_d(decay_rate_per_second, MPFR_RNDN);
-}
\ No newline at end of file
diff --git a/src/cpp/lib/DecayRate.h b/src/cpp/lib/DecayRate.h
deleted file mode 100644
index a66a68486..000000000
--- a/src/cpp/lib/DecayRate.h
+++ /dev/null
@@ -1,28 +0,0 @@
-#ifndef __GRADIDO_LOGIN_SERVER_LIB_INTEREST_RATE_H
-#define __GRADIDO_LOGIN_SERVER_LIB_INTEREST_RATE_H
-
-/*!
- * @author: Dario Rekowski
- * 
- * @date: 2020-11-24 
- *
- * @brief: to calculate interest rate for gradido and maybe also decay
-*/
-
-#include "Poco/Types.h"
-#include "Profiler.h"
-
-class DecayRate
-{
-public:
-	DecayRate();
-	~DecayRate();
-
-	void calculateDecayRate(int daysPerYear = 356, Profiler* time = nullptr);
-	inline double getDecayRate() { return mDecayRate; }
-
-protected:
-	double mDecayRate;
-};
-
-#endif //__GRADIDO_LOGIN_SERVER_LIB_INTEREST_RATE_H
\ No newline at end of file