diff --git a/authority/provisioner/aws.go b/authority/provisioner/aws.go
index a58ffb7e..74fa3a1f 100644
--- a/authority/provisioner/aws.go
+++ b/authority/provisioner/aws.go
@@ -469,7 +469,7 @@ func (p *AWS) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 		// Set the default extensions.
 		&sshDefaultExtensionModifier{},
 		// Set the validity bounds if not set.
-		sshDefaultValidityModifier(p.claimer),
+		&sshDefaultDuration{p.claimer},
 		// Validate public key
 		&sshDefaultPublicKeyValidator{},
 		// Validate the validity period.
diff --git a/authority/provisioner/azure.go b/authority/provisioner/azure.go
index 5e338e18..998ef6e1 100644
--- a/authority/provisioner/azure.go
+++ b/authority/provisioner/azure.go
@@ -209,7 +209,7 @@ func (p *Azure) Init(config Config) (err error) {
 	return nil
 }
 
-// parseToken returuns the claims, name, group, error.
+// parseToken returns the claims, name, group, error.
 func (p *Azure) parseToken(token string) (*azurePayload, string, string, error) {
 	jwt, err := jose.ParseSigned(token)
 	if err != nil {
@@ -335,7 +335,7 @@ func (p *Azure) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOptio
 		// Set the default extensions.
 		&sshDefaultExtensionModifier{},
 		// Set the validity bounds if not set.
-		sshDefaultValidityModifier(p.claimer),
+		&sshDefaultDuration{p.claimer},
 		// Validate public key
 		&sshDefaultPublicKeyValidator{},
 		// Validate the validity period.
diff --git a/authority/provisioner/claims.go b/authority/provisioner/claims.go
index 4eba5ad7..997d9ba3 100644
--- a/authority/provisioner/claims.go
+++ b/authority/provisioner/claims.go
@@ -4,6 +4,7 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+	"golang.org/x/crypto/ssh"
 )
 
 // Claims so that individual provisioners can override global claims.
@@ -95,6 +96,21 @@ func (c *Claimer) IsDisableRenewal() bool {
 	return *c.claims.DisableRenewal
 }
 
+// DefaultSSHCertDuration returns the default SSH certificate duration for the
+// given certificate type.
+func (c *Claimer) DefaultSSHCertDuration(certType uint32) (time.Duration, error) {
+	switch certType {
+	case ssh.UserCert:
+		return c.DefaultUserSSHCertDuration(), nil
+	case ssh.HostCert:
+		return c.DefaultHostSSHCertDuration(), nil
+	case 0:
+		return 0, errors.New("ssh certificate type has not been set")
+	default:
+		return 0, errors.Errorf("ssh certificate has an unknown type: %d", certType)
+	}
+}
+
 // DefaultUserSSHCertDuration returns the default SSH user cert duration for the
 // provisioner. If the default is not set within the provisioner, then the
 // global default from the authority configuration will be used.
diff --git a/authority/provisioner/claims_test.go b/authority/provisioner/claims_test.go
new file mode 100644
index 00000000..d4794d3c
--- /dev/null
+++ b/authority/provisioner/claims_test.go
@@ -0,0 +1,51 @@
+package provisioner
+
+import (
+	"testing"
+	"time"
+
+	"golang.org/x/crypto/ssh"
+)
+
+func TestClaimer_DefaultSSHCertDuration(t *testing.T) {
+	duration := Duration{
+		Duration: time.Hour,
+	}
+	type fields struct {
+		global Claims
+		claims *Claims
+	}
+	type args struct {
+		certType uint32
+	}
+	tests := []struct {
+		name    string
+		fields  fields
+		args    args
+		want    time.Duration
+		wantErr bool
+	}{
+		{"user", fields{globalProvisionerClaims, &Claims{DefaultUserSSHDur: &duration}}, args{1}, time.Hour, false},
+		{"user global", fields{globalProvisionerClaims, nil}, args{ssh.UserCert}, 16 * time.Hour, false},
+		{"host global", fields{globalProvisionerClaims, &Claims{DefaultHostSSHDur: &duration}}, args{2}, time.Hour, false},
+		{"host global", fields{globalProvisionerClaims, nil}, args{ssh.HostCert}, 30 * 24 * time.Hour, false},
+		{"invalid", fields{globalProvisionerClaims, nil}, args{0}, 0, true},
+		{"invalid global", fields{globalProvisionerClaims, nil}, args{3}, 0, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			c := &Claimer{
+				global: tt.fields.global,
+				claims: tt.fields.claims,
+			}
+			got, err := c.DefaultSSHCertDuration(tt.args.certType)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Claimer.DefaultSSHCertDuration() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("Claimer.DefaultSSHCertDuration() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/authority/provisioner/gcp.go b/authority/provisioner/gcp.go
index 30a65909..bc531e92 100644
--- a/authority/provisioner/gcp.go
+++ b/authority/provisioner/gcp.go
@@ -378,7 +378,7 @@ func (p *GCP) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 		// Set the default extensions
 		&sshDefaultExtensionModifier{},
 		// Set the validity bounds if not set.
-		sshDefaultValidityModifier(p.claimer),
+		&sshDefaultDuration{p.claimer},
 		// Validate public key
 		&sshDefaultPublicKeyValidator{},
 		// Validate the validity period.
diff --git a/authority/provisioner/jwk.go b/authority/provisioner/jwk.go
index 231b1580..b5add3f4 100644
--- a/authority/provisioner/jwk.go
+++ b/authority/provisioner/jwk.go
@@ -188,6 +188,7 @@ func (p *JWK) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 	if claims.Step == nil || claims.Step.SSH == nil {
 		return nil, errors.New("authorization token must be an SSH provisioning token")
 	}
+
 	opts := claims.Step.SSH
 	signOptions := []SignOption{
 		// validates user's SSHOptions with the ones in the token
@@ -222,7 +223,7 @@ func (p *JWK) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 		// Set the default extensions.
 		&sshDefaultExtensionModifier{},
 		// Set the validity bounds if not set.
-		sshDefaultValidityModifier(p.claimer),
+		&sshDefaultDuration{p.claimer},
 		// Validate that the keyID is equivalent to the token subject.
 		sshCertKeyIDValidator(claims.Subject),
 		// Validate public key
diff --git a/authority/provisioner/k8sSA.go b/authority/provisioner/k8sSA.go
index 0c90552c..e7d45236 100644
--- a/authority/provisioner/k8sSA.go
+++ b/authority/provisioner/k8sSA.go
@@ -235,13 +235,15 @@ func (p *K8sSA) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOptio
 	}
 
 	// Default to a user certificate with no principals if not set
-	signOptions := []SignOption{sshCertificateDefaultsModifier{CertType: SSHUserCert}}
+	signOptions := []SignOption{
+		sshCertificateDefaultsModifier{CertType: SSHUserCert},
+	}
 
 	return append(signOptions,
 		// Set the default extensions.
 		&sshDefaultExtensionModifier{},
 		// Set the validity bounds if not set.
-		sshDefaultValidityModifier(p.claimer),
+		&sshDefaultDuration{p.claimer},
 		// Validate public key
 		&sshDefaultPublicKeyValidator{},
 		// Validate the validity period.
diff --git a/authority/provisioner/oidc.go b/authority/provisioner/oidc.go
index 4538ef81..4c4b68d2 100644
--- a/authority/provisioner/oidc.go
+++ b/authority/provisioner/oidc.go
@@ -360,7 +360,7 @@ func (o *OIDC) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption
 		// Set the default extensions
 		&sshDefaultExtensionModifier{},
 		// Set the validity bounds if not set.
-		sshDefaultValidityModifier(o.claimer),
+		&sshDefaultDuration{o.claimer},
 		// Validate public key
 		&sshDefaultPublicKeyValidator{},
 		// Validate the validity period.
diff --git a/authority/provisioner/sign_options.go b/authority/provisioner/sign_options.go
index ddc985e3..2c3cfa16 100644
--- a/authority/provisioner/sign_options.go
+++ b/authority/provisioner/sign_options.go
@@ -267,12 +267,19 @@ func newValidityValidator(min, max time.Duration) *validityValidator {
 // and total duration.
 func (v *validityValidator) Valid(crt *x509.Certificate) error {
 	var (
-		na  = crt.NotAfter
-		nb  = crt.NotBefore
-		now = time.Now()
+		na  = crt.NotAfter.Truncate(time.Second)
+		nb  = crt.NotBefore.Truncate(time.Second)
+		now = time.Now().Truncate(time.Second)
 	)
-	// Get duration from to not take into account the backdate.
-	var d = na.Sub(now)
+
+	// To not take into account the backdate, time.Now() will be used to
+	// calculate the duration if NotBefore is in the past.
+	var d time.Duration
+	if now.After(nb) {
+		d = na.Sub(now)
+	} else {
+		d = na.Sub(nb)
+	}
 
 	if na.Before(now) {
 		return errors.Errorf("NotAfter: %v cannot be in the past", na)
diff --git a/authority/provisioner/sign_ssh_options.go b/authority/provisioner/sign_ssh_options.go
index ceb57105..f5ad8662 100644
--- a/authority/provisioner/sign_ssh_options.go
+++ b/authority/provisioner/sign_ssh_options.go
@@ -46,13 +46,22 @@ type SSHCertificateOptionsValidator interface {
 	Valid(got SSHOptions) error
 }
 
+// sshModifierFunc is an adapter to allow the use of ordinary functions as SSH
+// certificate modifiers.
+type sshModifierFunc func(cert *ssh.Certificate) error
+
+func (f sshModifierFunc) Modify(cert *ssh.Certificate) error {
+	return f(cert)
+}
+
 // SSHOptions contains the options that can be passed to the SignSSH method.
 type SSHOptions struct {
-	CertType    string       `json:"certType"`
-	KeyID       string       `json:"keyID"`
-	Principals  []string     `json:"principals"`
-	ValidAfter  TimeDuration `json:"validAfter,omitempty"`
-	ValidBefore TimeDuration `json:"validBefore,omitempty"`
+	CertType    string        `json:"certType"`
+	KeyID       string        `json:"keyID"`
+	Principals  []string      `json:"principals"`
+	ValidAfter  TimeDuration  `json:"validAfter,omitempty"`
+	ValidBefore TimeDuration  `json:"validBefore,omitempty"`
+	Backdate    time.Duration `json:"-"`
 }
 
 // Type returns the uint32 representation of the CertType.
@@ -199,67 +208,92 @@ func (m *sshDefaultExtensionModifier) Modify(cert *ssh.Certificate) error {
 	}
 }
 
-// sshValidityModifier is an SSHCertificateModifier that checks the
-// validity bounds, setting them if they are not provided. It will fail if a
+// sshDefaultDuration is an SSHCertificateModifier that sets the certificate
+// ValidAfter and ValidBefore if they have not been set. It will fail if a
 // CertType has not been set or is not valid.
-type sshValidityModifier struct {
+type sshDefaultDuration struct {
 	*Claimer
-	validBefore time.Time
 }
 
-func (m *sshValidityModifier) Modify(cert *ssh.Certificate) error {
-	var d time.Duration
+func (m *sshDefaultDuration) Option(o SSHOptions) SSHCertificateModifier {
+	return sshModifierFunc(func(cert *ssh.Certificate) error {
+		d, err := m.DefaultSSHCertDuration(cert.CertType)
+		if err != nil {
+			return err
+		}
 
-	switch cert.CertType {
-	case ssh.UserCert:
-		d = m.DefaultUserSSHCertDuration()
-	case ssh.HostCert:
-		d = m.DefaultHostSSHCertDuration()
-	case 0:
-		return errors.New("ssh certificate type has not been set")
-	default:
-		return errors.Errorf("unknown ssh certificate type %d", cert.CertType)
-	}
+		var backdate uint64
+		if cert.ValidAfter == 0 {
+			backdate = uint64(o.Backdate / time.Second)
+			cert.ValidAfter = uint64(now().Truncate(time.Second).Unix())
+		}
+		if cert.ValidBefore == 0 {
+			cert.ValidBefore = cert.ValidAfter + uint64(d/time.Second)
+		}
+		// Apply backdate safely
+		if cert.ValidAfter > backdate {
+			cert.ValidAfter -= backdate
+		}
+		return nil
+	})
+}
 
-	hasLimit := !m.validBefore.IsZero()
+// sshLimitDuration adjusts the duration to min(default, remaining provisioning
+// credential duration). E.g. if the default is 12hrs but the remaining validity
+// of the provisioning credential is only 4hrs, this option will set the value
+// to 4hrs (the min of the two values). It will fail if a CertType has not been
+// set or is not valid.
+type sshLimitDuration struct {
+	*Claimer
+	NotAfter time.Time
+}
 
-	n := now()
-	if cert.ValidAfter == 0 {
-		cert.ValidAfter = uint64(n.Truncate(time.Second).Unix())
-	}
-	certValidAfter := time.Unix(int64(cert.ValidAfter), 0)
-	if hasLimit && certValidAfter.After(m.validBefore) {
-		return errors.Errorf("provisioning credential expiration (%s) is before "+
-			"requested certificate validAfter (%s)", m.validBefore, certValidAfter)
+func (m *sshLimitDuration) Option(o SSHOptions) SSHCertificateModifier {
+	if m.NotAfter.IsZero() {
+		defaultDuration := &sshDefaultDuration{m.Claimer}
+		return defaultDuration.Option(o)
 	}
 
-	if cert.ValidBefore == 0 {
-		certValidBefore := certValidAfter.Add(d)
-		if hasLimit && m.validBefore.Before(certValidBefore) {
-			certValidBefore = m.validBefore
+	return sshModifierFunc(func(cert *ssh.Certificate) error {
+		d, err := m.DefaultSSHCertDuration(cert.CertType)
+		if err != nil {
+			return err
 		}
-		cert.ValidBefore = uint64(certValidBefore.Unix())
-	} else if hasLimit {
-		certValidBefore := time.Unix(int64(cert.ValidBefore), 0)
-		if m.validBefore.Before(certValidBefore) {
-			return errors.Errorf("provisioning credential expiration (%s) is before "+
-				"requested certificate validBefore (%s)", m.validBefore, certValidBefore)
+
+		var backdate uint64
+		if cert.ValidAfter == 0 {
+			backdate = uint64(o.Backdate / time.Second)
+			cert.ValidAfter = uint64(now().Truncate(time.Second).Unix())
 		}
-	}
 
-	return nil
-}
+		certValidAfter := time.Unix(int64(cert.ValidAfter), 0)
+		if certValidAfter.After(m.NotAfter) {
+			return errors.Errorf("provisioning credential expiration (%s) is before requested certificate validAfter (%s)",
+				m.NotAfter, certValidAfter)
+		}
 
-func sshDefaultValidityModifier(c *Claimer) SSHCertificateModifier {
-	return &sshValidityModifier{c, time.Time{}}
-}
+		if cert.ValidBefore == 0 {
+			certValidBefore := certValidAfter.Add(d)
+			if m.NotAfter.Before(certValidBefore) {
+				certValidBefore = m.NotAfter
+				println(2, certValidBefore.String())
+			}
+			cert.ValidBefore = uint64(certValidBefore.Unix())
+		} else {
+			certValidBefore := time.Unix(int64(cert.ValidBefore), 0)
+			if m.NotAfter.Before(certValidBefore) {
+				return errors.Errorf("provisioning credential expiration (%s) is before requested certificate validBefore (%s)",
+					m.NotAfter, certValidBefore)
+			}
+		}
 
-// sshLimitValidityModifier adjusts the duration to
-// min(default, remaining provisioning credential duration).
-// E.g. if the default is 12hrs but the remaining validity of the provisioning
-// credential is only 4hrs, this option will set the value to 4hrs (the min of the two values).
-func sshLimitValidityModifier(c *Claimer, validBefore time.Time) SSHCertificateModifier {
-	return &sshValidityModifier{c, validBefore}
+		// Apply backdate safely
+		if cert.ValidAfter > backdate {
+			cert.ValidAfter -= backdate
+		}
+
+		return nil
+	})
 }
 
 // sshCertificateOptionsValidator validates the user SSHOptions with the ones
@@ -301,8 +335,15 @@ func (v *sshCertificateValidityValidator) Valid(cert *ssh.Certificate) error {
 		return errors.Errorf("unknown ssh certificate type %d", cert.CertType)
 	}
 
-	// seconds
-	dur := time.Duration(cert.ValidBefore-cert.ValidAfter) * time.Second
+	// To not take into account the backdate, time.Now() will be used to
+	// calculate the duration if ValidAfter is in the past.
+	var dur time.Duration
+	if t := now().Unix(); t > int64(cert.ValidAfter) {
+		dur = time.Duration(int64(cert.ValidBefore)-t) * time.Second
+	} else {
+		dur = time.Duration(cert.ValidBefore-cert.ValidAfter) * time.Second
+	}
+
 	switch {
 	case dur < min:
 		return errors.Errorf("requested duration of %s is less than minimum "+
diff --git a/authority/provisioner/sign_ssh_options_test.go b/authority/provisioner/sign_ssh_options_test.go
index 25a44121..3db0f95e 100644
--- a/authority/provisioner/sign_ssh_options_test.go
+++ b/authority/provisioner/sign_ssh_options_test.go
@@ -1,6 +1,7 @@
 package provisioner
 
 import (
+	"fmt"
 	"testing"
 	"time"
 
@@ -10,6 +11,32 @@ import (
 	"golang.org/x/crypto/ssh"
 )
 
+func TestSSHOptions_Type(t *testing.T) {
+	type fields struct {
+		CertType string
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		want   uint32
+	}{
+		{"user", fields{"user"}, 1},
+		{"host", fields{"host"}, 2},
+		{"empty", fields{""}, 0},
+		{"invalid", fields{"invalid"}, 0},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			o := SSHOptions{
+				CertType: tt.fields.CertType,
+			}
+			if got := o.Type(); got != tt.want {
+				t.Errorf("SSHOptions.Type() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
 func Test_sshCertificateDefaultValidator_Valid(t *testing.T) {
 	pub, _, err := keys.GenerateDefaultKeyPair()
 	assert.FatalError(t, err)
@@ -276,7 +303,7 @@ func Test_sshValidityModifier(t *testing.T) {
 	p, err := generateX5C(nil)
 	assert.FatalError(t, err)
 	type test struct {
-		svm   *sshValidityModifier
+		svm   *sshLimitDuration
 		cert  *ssh.Certificate
 		valid func(*ssh.Certificate)
 		err   error
@@ -284,7 +311,7 @@ func Test_sshValidityModifier(t *testing.T) {
 	tests := map[string]func() test{
 		"fail/type-not-set": func() test {
 			return test{
-				svm: &sshValidityModifier{Claimer: p.claimer, validBefore: n.Add(6 * time.Hour)},
+				svm: &sshLimitDuration{Claimer: p.claimer, NotAfter: n.Add(6 * time.Hour)},
 				cert: &ssh.Certificate{
 					ValidAfter:  uint64(n.Unix()),
 					ValidBefore: uint64(n.Add(8 * time.Hour).Unix()),
@@ -294,18 +321,18 @@ func Test_sshValidityModifier(t *testing.T) {
 		},
 		"fail/type-not-recognized": func() test {
 			return test{
-				svm: &sshValidityModifier{Claimer: p.claimer, validBefore: n.Add(6 * time.Hour)},
+				svm: &sshLimitDuration{Claimer: p.claimer, NotAfter: n.Add(6 * time.Hour)},
 				cert: &ssh.Certificate{
 					CertType:    4,
 					ValidAfter:  uint64(n.Unix()),
 					ValidBefore: uint64(n.Add(8 * time.Hour).Unix()),
 				},
-				err: errors.New("unknown ssh certificate type 4"),
+				err: errors.New("ssh certificate has an unknown type: 4"),
 			}
 		},
 		"fail/requested-validAfter-after-limit": func() test {
 			return test{
-				svm: &sshValidityModifier{Claimer: p.claimer, validBefore: n.Add(1 * time.Hour)},
+				svm: &sshLimitDuration{Claimer: p.claimer, NotAfter: n.Add(1 * time.Hour)},
 				cert: &ssh.Certificate{
 					CertType:    1,
 					ValidAfter:  uint64(n.Add(2 * time.Hour).Unix()),
@@ -316,7 +343,7 @@ func Test_sshValidityModifier(t *testing.T) {
 		},
 		"fail/requested-validBefore-after-limit": func() test {
 			return test{
-				svm: &sshValidityModifier{Claimer: p.claimer, validBefore: n.Add(1 * time.Hour)},
+				svm: &sshLimitDuration{Claimer: p.claimer, NotAfter: n.Add(1 * time.Hour)},
 				cert: &ssh.Certificate{
 					CertType:    1,
 					ValidAfter:  uint64(n.Unix()),
@@ -328,7 +355,7 @@ func Test_sshValidityModifier(t *testing.T) {
 		"ok/valid-requested-validBefore": func() test {
 			va, vb := uint64(n.Unix()), uint64(n.Add(2*time.Hour).Unix())
 			return test{
-				svm: &sshValidityModifier{Claimer: p.claimer, validBefore: n.Add(3 * time.Hour)},
+				svm: &sshLimitDuration{Claimer: p.claimer, NotAfter: n.Add(3 * time.Hour)},
 				cert: &ssh.Certificate{
 					CertType:    1,
 					ValidAfter:  va,
@@ -343,21 +370,21 @@ func Test_sshValidityModifier(t *testing.T) {
 		"ok/empty-requested-validBefore-limit-after-default": func() test {
 			va := uint64(n.Unix())
 			return test{
-				svm: &sshValidityModifier{Claimer: p.claimer, validBefore: n.Add(5 * time.Hour)},
+				svm: &sshLimitDuration{Claimer: p.claimer, NotAfter: n.Add(24 * time.Hour)},
 				cert: &ssh.Certificate{
 					CertType:   1,
 					ValidAfter: va,
 				},
 				valid: func(cert *ssh.Certificate) {
 					assert.Equals(t, cert.ValidAfter, va)
-					assert.Equals(t, cert.ValidBefore, uint64(n.Add(4*time.Hour).Unix()))
+					assert.Equals(t, cert.ValidBefore, uint64(n.Add(16*time.Hour).Unix()))
 				},
 			}
 		},
 		"ok/empty-requested-validBefore-limit-before-default": func() test {
 			va := uint64(n.Unix())
 			return test{
-				svm: &sshValidityModifier{Claimer: p.claimer, validBefore: n.Add(3 * time.Hour)},
+				svm: &sshLimitDuration{Claimer: p.claimer, NotAfter: n.Add(3 * time.Hour)},
 				cert: &ssh.Certificate{
 					CertType:   1,
 					ValidAfter: va,
@@ -372,7 +399,7 @@ func Test_sshValidityModifier(t *testing.T) {
 	for name, run := range tests {
 		t.Run(name, func(t *testing.T) {
 			tt := run()
-			if err := tt.svm.Modify(tt.cert); err != nil {
+			if err := tt.svm.Option(SSHOptions{}).Modify(tt.cert); err != nil {
 				if assert.NotNil(t, tt.err) {
 					assert.HasPrefix(t, err.Error(), tt.err.Error())
 				}
@@ -384,3 +411,25 @@ func Test_sshValidityModifier(t *testing.T) {
 		})
 	}
 }
+
+func Test_sshModifierFunc_Modify(t *testing.T) {
+	type args struct {
+		cert *ssh.Certificate
+	}
+	tests := []struct {
+		name    string
+		f       sshModifierFunc
+		args    args
+		wantErr bool
+	}{
+		{"ok", func(cert *ssh.Certificate) error { return nil }, args{&ssh.Certificate{}}, false},
+		{"fail", func(cert *ssh.Certificate) error { return fmt.Errorf("an error") }, args{&ssh.Certificate{}}, true},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if err := tt.f.Modify(tt.args.cert); (err != nil) != tt.wantErr {
+				t.Errorf("sshModifierFunc.Modify() error = %v, wantErr %v", err, tt.wantErr)
+			}
+		})
+	}
+}
diff --git a/authority/provisioner/utils_test.go b/authority/provisioner/utils_test.go
index f02c53b4..76c9a567 100644
--- a/authority/provisioner/utils_test.go
+++ b/authority/provisioner/utils_test.go
@@ -31,7 +31,7 @@ var (
 		DisableRenewal:    &defaultDisableRenewal,
 		MinUserSSHDur:     &Duration{Duration: 5 * time.Minute}, // User SSH certs
 		MaxUserSSHDur:     &Duration{Duration: 24 * time.Hour},
-		DefaultUserSSHDur: &Duration{Duration: 4 * time.Hour},
+		DefaultUserSSHDur: &Duration{Duration: 16 * time.Hour},
 		MinHostSSHDur:     &Duration{Duration: 5 * time.Minute}, // Host SSH certs
 		MaxHostSSHDur:     &Duration{Duration: 30 * 24 * time.Hour},
 		DefaultHostSSHDur: &Duration{Duration: 30 * 24 * time.Hour},
diff --git a/authority/provisioner/x5c.go b/authority/provisioner/x5c.go
index 651cd136..1be728db 100644
--- a/authority/provisioner/x5c.go
+++ b/authority/provisioner/x5c.go
@@ -228,6 +228,7 @@ func (p *X5C) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 	if claims.Step == nil || claims.Step.SSH == nil {
 		return nil, errors.New("authorization token must be an SSH provisioning token")
 	}
+
 	opts := claims.Step.SSH
 	signOptions := []SignOption{
 		// validates user's SSHOptions with the ones in the token
@@ -261,7 +262,7 @@ func (p *X5C) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption,
 		// Set the default extensions.
 		&sshDefaultExtensionModifier{},
 		// Checks the validity bounds, and set the validity if has not been set.
-		sshLimitValidityModifier(p.claimer, claims.chains[0][0].NotAfter),
+		&sshLimitDuration{p.claimer, claims.chains[0][0].NotAfter},
 		// set the key id to the token subject
 		sshCertKeyIDValidator(claims.Subject),
 		// Validate public key.
diff --git a/authority/provisioner/x5c_test.go b/authority/provisioner/x5c_test.go
index 94018b55..65147d24 100644
--- a/authority/provisioner/x5c_test.go
+++ b/authority/provisioner/x5c_test.go
@@ -646,9 +646,9 @@ func TestX5C_AuthorizeSSHSign(t *testing.T) {
 								assert.Equals(t, int64(v), tc.claims.Step.SSH.ValidBefore.RelativeTime(nw).Unix())
 							case sshCertificateDefaultsModifier:
 								assert.Equals(t, SSHOptions(v), SSHOptions{CertType: SSHUserCert})
-							case *sshValidityModifier:
+							case *sshLimitDuration:
 								assert.Equals(t, v.Claimer, tc.p.claimer)
-								assert.Equals(t, v.validBefore, tc.claims.chains[0][0].NotAfter)
+								assert.Equals(t, v.NotAfter, tc.claims.chains[0][0].NotAfter)
 							case *sshCertificateValidityValidator:
 								assert.Equals(t, v.Claimer, tc.p.claimer)
 							case *sshDefaultExtensionModifier, *sshDefaultPublicKeyValidator,
diff --git a/authority/ssh.go b/authority/ssh.go
index 8148a6bd..e5b2955a 100644
--- a/authority/ssh.go
+++ b/authority/ssh.go
@@ -209,6 +209,9 @@ func (a *Authority) SignSSH(key ssh.PublicKey, opts provisioner.SSHOptions, sign
 	var mods []provisioner.SSHCertificateModifier
 	var validators []provisioner.SSHCertificateValidator
 
+	// Set backdate with the configured value
+	opts.Backdate = a.config.AuthorityConfig.Backdate.Duration
+
 	for _, op := range signOpts {
 		switch o := op.(type) {
 		// modify the ssh.Certificate
@@ -365,9 +368,12 @@ func (a *Authority) RenewSSH(oldCert *ssh.Certificate) (*ssh.Certificate, error)
 	if oldCert.ValidAfter == 0 || oldCert.ValidBefore == 0 {
 		return nil, errors.New("rewnewSSH: cannot renew certificate without validity period")
 	}
-	dur := time.Duration(oldCert.ValidBefore-oldCert.ValidAfter) * time.Second
-	va := time.Now()
-	vb := va.Add(dur)
+
+	backdate := a.config.AuthorityConfig.Backdate.Duration
+	duration := time.Duration(oldCert.ValidBefore-oldCert.ValidAfter) * time.Second
+	now := time.Now()
+	va := now.Add(-1 * backdate)
+	vb := now.Add(duration - backdate)
 
 	// Build base certificate with the key and some random values
 	cert := &ssh.Certificate{