diff --git a/alphabet/alphabet.tpl b/alphabet/alphabet.tpl
index 963b04d..0753850 100644
--- a/alphabet/alphabet.tpl
+++ b/alphabet/alphabet.tpl
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,8 +34,6 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
 	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
diff --git a/alphabet/az/az_contract.go b/alphabet/az/az_contract.go
index 32d9d22..5fabb17 100644
--- a/alphabet/az/az_contract.go
+++ b/alphabet/az/az_contract.go
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,9 +34,7 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
-	threshold = totalAlphabetContracts*2/3 + 1
+	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
 	totalAlphabetContracts = 7
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
@@ -259,7 +265,7 @@ func bytesEqual(a []byte, b []byte) bool {
 
 func voteID(epoch interface{}, args [][]byte) []byte {
 	var (
-		result     []byte
+		result []byte
 		epochBytes = epoch.([]byte)
 	)
 
diff --git a/alphabet/buky/buky_contract.go b/alphabet/buky/buky_contract.go
index 0bd270d..5fb1974 100644
--- a/alphabet/buky/buky_contract.go
+++ b/alphabet/buky/buky_contract.go
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,9 +34,7 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
-	threshold = totalAlphabetContracts*2/3 + 1
+	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
 	totalAlphabetContracts = 7
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
@@ -259,7 +265,7 @@ func bytesEqual(a []byte, b []byte) bool {
 
 func voteID(epoch interface{}, args [][]byte) []byte {
 	var (
-		result     []byte
+		result []byte
 		epochBytes = epoch.([]byte)
 	)
 
diff --git a/alphabet/dobro/dobro_contract.go b/alphabet/dobro/dobro_contract.go
index aaa72df..91bd198 100644
--- a/alphabet/dobro/dobro_contract.go
+++ b/alphabet/dobro/dobro_contract.go
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,9 +34,7 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
-	threshold = totalAlphabetContracts*2/3 + 1
+	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
 	totalAlphabetContracts = 7
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
@@ -259,7 +265,7 @@ func bytesEqual(a []byte, b []byte) bool {
 
 func voteID(epoch interface{}, args [][]byte) []byte {
 	var (
-		result     []byte
+		result []byte
 		epochBytes = epoch.([]byte)
 	)
 
diff --git a/alphabet/glagoli/glagoli_contract.go b/alphabet/glagoli/glagoli_contract.go
index 377f70a..0ec7c33 100644
--- a/alphabet/glagoli/glagoli_contract.go
+++ b/alphabet/glagoli/glagoli_contract.go
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,9 +34,7 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
-	threshold = totalAlphabetContracts*2/3 + 1
+	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
 	totalAlphabetContracts = 7
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
@@ -259,7 +265,7 @@ func bytesEqual(a []byte, b []byte) bool {
 
 func voteID(epoch interface{}, args [][]byte) []byte {
 	var (
-		result     []byte
+		result []byte
 		epochBytes = epoch.([]byte)
 	)
 
diff --git a/alphabet/jest/jest_contract.go b/alphabet/jest/jest_contract.go
index 2415477..3e9b8fa 100644
--- a/alphabet/jest/jest_contract.go
+++ b/alphabet/jest/jest_contract.go
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,9 +34,7 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
-	threshold = totalAlphabetContracts*2/3 + 1
+	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
 	totalAlphabetContracts = 7
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
@@ -259,7 +265,7 @@ func bytesEqual(a []byte, b []byte) bool {
 
 func voteID(epoch interface{}, args [][]byte) []byte {
 	var (
-		result     []byte
+		result []byte
 		epochBytes = epoch.([]byte)
 	)
 
diff --git a/alphabet/vedi/vedi_contract.go b/alphabet/vedi/vedi_contract.go
index 565e820..9ad5311 100644
--- a/alphabet/vedi/vedi_contract.go
+++ b/alphabet/vedi/vedi_contract.go
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,9 +34,7 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
-	threshold = totalAlphabetContracts*2/3 + 1
+	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
 	totalAlphabetContracts = 7
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
@@ -259,7 +265,7 @@ func bytesEqual(a []byte, b []byte) bool {
 
 func voteID(epoch interface{}, args [][]byte) []byte {
 	var (
-		result     []byte
+		result []byte
 		epochBytes = epoch.([]byte)
 	)
 
diff --git a/alphabet/zhivete/zhivete_contract.go b/alphabet/zhivete/zhivete_contract.go
index 4480b52..d7d9dd6 100644
--- a/alphabet/zhivete/zhivete_contract.go
+++ b/alphabet/zhivete/zhivete_contract.go
@@ -2,7 +2,6 @@ package alphabetcontract
 
 import (
 	"github.com/nspcc-dev/neo-go/pkg/interop/binary"
-	"github.com/nspcc-dev/neo-go/pkg/interop/blockchain"
 	"github.com/nspcc-dev/neo-go/pkg/interop/contract"
 	"github.com/nspcc-dev/neo-go/pkg/interop/crypto"
 	"github.com/nspcc-dev/neo-go/pkg/interop/engine"
@@ -17,9 +16,9 @@ type (
 	}
 
 	ballot struct {
-		id    []byte   // id of the voting decision
-		n     [][]byte // already voted inner ring nodes
-		block int      // block with the last vote
+		id     []byte   // hash of validators list
+		n      [][]byte // already voted inner ring nodes
+		height int      // height is an neofs epoch when ballot was registered
 	}
 )
 
@@ -35,9 +34,7 @@ const (
 
 	netmapContractKey = "netmapScriptHash"
 
-	blockDiff = 20 // amount of blocks when ballot get discarded
-
-	threshold = totalAlphabetContracts*2/3 + 1
+	threshold = totalAlphabetContracts * 2 / 3 + 1
 	voteKey   = "ballots"
 
 	totalAlphabetContracts = 7
@@ -91,6 +88,11 @@ func irList() []irNode {
 	return engine.AppCall(netmapContractAddr, "innerRingList").([]irNode)
 }
 
+func currentEpoch() int {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	return engine.AppCall(netmapContractAddr, "epoch").(int)
+}
+
 func checkPermission(ir []irNode) bool {
 	if len(ir) <= index {
 		return false
@@ -153,8 +155,13 @@ func Vote(epoch int, candidates [][]byte) {
 		panic("invalid invoker")
 	}
 
+	curEpoch := currentEpoch()
+	if epoch != curEpoch {
+		panic("invalid epoch")
+	}
+
 	id := voteID(epoch, candidates)
-	n := vote(ctx, id, key)
+	n := vote(ctx, curEpoch, id, key)
 
 	if n >= threshold {
 		candidate := candidates[index%len(candidates)]
@@ -178,12 +185,11 @@ func Name() string {
 	return name
 }
 
-func vote(ctx storage.Context, id, from []byte) int {
+func vote(ctx storage.Context, epoch int, id, from []byte) int {
 	var (
 		newCandidates []ballot
 		candidates    = getBallots(ctx)
 		found         = -1
-		blockHeight   = blockchain.GetHeight()
 	)
 
 	for i := 0; i < len(candidates); i++ {
@@ -198,12 +204,12 @@ func vote(ctx storage.Context, id, from []byte) int {
 			}
 
 			voters = append(voters, from)
-			cnd = ballot{id: id, n: voters, block: blockHeight}
+			cnd = ballot{id: id, n: voters, height: epoch}
 			found = len(voters)
 		}
 
-		// do not add old ballots, they are invalid
-		if blockHeight-cnd.block <= blockDiff {
+		// add only valid ballots with current epochs
+		if cnd.height == epoch {
 			newCandidates = append(newCandidates, cnd)
 		}
 	}
@@ -211,9 +217,9 @@ func vote(ctx storage.Context, id, from []byte) int {
 	if found < 0 {
 		voters := [][]byte{from}
 		newCandidates = append(newCandidates, ballot{
-			id:    id,
-			n:     voters,
-			block: blockHeight})
+			id:     id,
+			n:      voters,
+			height: epoch})
 		found = 1
 	}
 
@@ -259,7 +265,7 @@ func bytesEqual(a []byte, b []byte) bool {
 
 func voteID(epoch interface{}, args [][]byte) []byte {
 	var (
-		result     []byte
+		result []byte
 		epochBytes = epoch.([]byte)
 	)