diff --git a/src/main/java/org/qortal/block/Block.java b/src/main/java/org/qortal/block/Block.java
index bbd62dd3..a31c522b 100644
--- a/src/main/java/org/qortal/block/Block.java
+++ b/src/main/java/org/qortal/block/Block.java
@@ -1461,6 +1461,9 @@ public class Block {
 			if (this.blockData.getHeight() == 212937)
 				// Apply fix for block 212937
 				Block212937.processFix(this);
+
+			else if (this.blockData.getHeight() == BlockChain.getInstance().getSelfSponsorshipAlgoV1Height())
+				SelfSponsorshipAlgoV1Block.processAccountPenalties(this);
 		}
 
 		// We're about to (test-)process a batch of transactions,
@@ -1696,6 +1699,9 @@ public class Block {
 				// Revert fix for block 212937
 				Block212937.orphanFix(this);
 
+			else if (this.blockData.getHeight() == BlockChain.getInstance().getSelfSponsorshipAlgoV1Height())
+				SelfSponsorshipAlgoV1Block.orphanAccountPenalties(this);
+
 			// Block rewards, including transaction fees, removed after transactions undone
 			orphanBlockRewards();
 
diff --git a/src/main/java/org/qortal/block/SelfSponsorshipAlgoV1Block.java b/src/main/java/org/qortal/block/SelfSponsorshipAlgoV1Block.java
new file mode 100644
index 00000000..a9a016b6
--- /dev/null
+++ b/src/main/java/org/qortal/block/SelfSponsorshipAlgoV1Block.java
@@ -0,0 +1,133 @@
+package org.qortal.block;
+
+import org.apache.commons.lang3.StringUtils;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.qortal.account.SelfSponsorshipAlgoV1;
+import org.qortal.api.model.AccountPenaltyStats;
+import org.qortal.crypto.Crypto;
+import org.qortal.data.account.AccountData;
+import org.qortal.data.account.AccountPenaltyData;
+import org.qortal.repository.DataException;
+import org.qortal.repository.Repository;
+import org.qortal.utils.Base58;
+
+import java.nio.charset.StandardCharsets;
+import java.util.*;
+import java.util.stream.Collectors;
+
+/**
+ * Self Sponsorship AlgoV1 Block
+ * <p>
+ * Selected block for the initial run on the "self sponsorship detection algorithm"
+ */
+public final class SelfSponsorshipAlgoV1Block {
+
+	private static final Logger LOGGER = LogManager.getLogger(SelfSponsorshipAlgoV1Block.class);
+
+
+	private SelfSponsorshipAlgoV1Block() {
+		/* Do not instantiate */
+	}
+
+	public static void processAccountPenalties(Block block) throws DataException {
+		LOGGER.info("Running algo for block processing - this will take a while...");
+		logPenaltyStats(block.repository);
+		long startTime = System.currentTimeMillis();
+		Set<AccountPenaltyData> penalties = getAccountPenalties(block.repository, -5000000);
+		block.repository.getAccountRepository().updateBlocksMintedPenalties(penalties);
+		long totalTime = System.currentTimeMillis() - startTime;
+		String hash = getHash(penalties.stream().map(p -> p.getAddress()).collect(Collectors.toList()));
+		LOGGER.info("{} penalty addresses processed (hash: {}). Total time taken: {} seconds", penalties.size(), hash, (int)(totalTime / 1000.0f));
+		logPenaltyStats(block.repository);
+
+		int updatedCount = updateAccountLevels(block.repository, penalties);
+		LOGGER.info("Account levels updated for {} penalty addresses", updatedCount);
+	}
+
+	public static void orphanAccountPenalties(Block block) throws DataException {
+		LOGGER.info("Running algo for block orphaning - this will take a while...");
+		logPenaltyStats(block.repository);
+		long startTime = System.currentTimeMillis();
+		Set<AccountPenaltyData> penalties = getAccountPenalties(block.repository, 5000000);
+		block.repository.getAccountRepository().updateBlocksMintedPenalties(penalties);
+		long totalTime = System.currentTimeMillis() - startTime;
+		String hash = getHash(penalties.stream().map(p -> p.getAddress()).collect(Collectors.toList()));
+		LOGGER.info("{} penalty addresses orphaned (hash: {}). Total time taken: {} seconds", penalties.size(), hash, (int)(totalTime / 1000.0f));
+		logPenaltyStats(block.repository);
+
+		int updatedCount = updateAccountLevels(block.repository, penalties);
+		LOGGER.info("Account levels updated for {} penalty addresses", updatedCount);
+	}
+
+	public static Set<AccountPenaltyData> getAccountPenalties(Repository repository, int penalty) throws DataException {
+		final long snapshotTimestamp = BlockChain.getInstance().getSelfSponsorshipAlgoV1SnapshotTimestamp();
+		Set<AccountPenaltyData> penalties = new LinkedHashSet<>();
+		List<String> addresses = repository.getTransactionRepository().getConfirmedRewardShareCreatorsExcludingSelfShares();
+		for (String address : addresses) {
+			//System.out.println(String.format("address: %s", address));
+			SelfSponsorshipAlgoV1 selfSponsorshipAlgoV1 = new SelfSponsorshipAlgoV1(repository, address, snapshotTimestamp, false);
+			selfSponsorshipAlgoV1.run();
+			//System.out.println(String.format("Penalty addresses: %d", selfSponsorshipAlgoV1.getPenaltyAddresses().size()));
+
+			for (String penaltyAddress : selfSponsorshipAlgoV1.getPenaltyAddresses()) {
+				penalties.add(new AccountPenaltyData(penaltyAddress, penalty));
+			}
+		}
+		return penalties;
+	}
+
+	private static int updateAccountLevels(Repository repository, Set<AccountPenaltyData> accountPenalties) throws DataException {
+		final List<Integer> cumulativeBlocksByLevel = BlockChain.getInstance().getCumulativeBlocksByLevel();
+		final int maximumLevel = cumulativeBlocksByLevel.size() - 1;
+
+		int updatedCount = 0;
+
+		for (AccountPenaltyData penaltyData : accountPenalties) {
+			AccountData accountData = repository.getAccountRepository().getAccount(penaltyData.getAddress());
+			final int effectiveBlocksMinted = accountData.getBlocksMinted() + accountData.getBlocksMintedAdjustment() + accountData.getBlocksMintedPenalty();
+
+			// Shortcut for penalties
+			if (effectiveBlocksMinted < 0) {
+				accountData.setLevel(0);
+				repository.getAccountRepository().setLevel(accountData);
+				updatedCount++;
+				LOGGER.trace(() -> String.format("Block minter %s dropped to level %d", accountData.getAddress(), accountData.getLevel()));
+				continue;
+			}
+
+			for (int newLevel = maximumLevel; newLevel >= 0; --newLevel) {
+				if (effectiveBlocksMinted >= cumulativeBlocksByLevel.get(newLevel)) {
+					accountData.setLevel(newLevel);
+					repository.getAccountRepository().setLevel(accountData);
+					updatedCount++;
+					LOGGER.trace(() -> String.format("Block minter %s increased to level %d", accountData.getAddress(), accountData.getLevel()));
+					break;
+				}
+			}
+		}
+
+		return updatedCount;
+	}
+
+	private static void logPenaltyStats(Repository repository) {
+		try {
+			LOGGER.info(getPenaltyStats(repository));
+
+		} catch (DataException e) {}
+	}
+
+	private static AccountPenaltyStats getPenaltyStats(Repository repository) throws DataException {
+		List<AccountData> accounts = repository.getAccountRepository().getPenaltyAccounts();
+		return AccountPenaltyStats.fromAccounts(accounts);
+	}
+
+	public static String getHash(List<String> penaltyAddresses) {
+		if (penaltyAddresses == null || penaltyAddresses.isEmpty()) {
+			return null;
+		}
+		Collections.sort(penaltyAddresses);
+		return Base58.encode(Crypto.digest(StringUtils.join(penaltyAddresses).getBytes(StandardCharsets.UTF_8)));
+	}
+
+}