diff --git a/app/Services/Internal/Support/CreditRecalculateService.php b/app/Services/Internal/Support/CreditRecalculateService.php
new file mode 100644
index 0000000000..2cbc5d6279
--- /dev/null
+++ b/app/Services/Internal/Support/CreditRecalculateService.php
@@ -0,0 +1,156 @@
+<?php
+/*
+ * CreditRecalculateService.php
+ * Copyright (c) 2021 james@firefly-iii.org
+ *
+ * This file is part of Firefly III (https://github.com/firefly-iii).
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace FireflyIII\Services\Internal\Support;
+
+
+use FireflyIII\Exceptions\FireflyException;
+use FireflyIII\Models\Account;
+use FireflyIII\Models\AccountType;
+use FireflyIII\Models\Transaction;
+use FireflyIII\Models\TransactionGroup;
+use FireflyIII\Models\TransactionJournal;
+use FireflyIII\Models\TransactionType;
+use FireflyIII\Repositories\Account\AccountRepositoryInterface;
+use Log;
+
+class CreditRecalculateService
+{
+    private TransactionGroup $group;
+
+    /**
+     *
+     */
+    public function recalculate(): void
+    {
+        if (true !== config('firefly.feature_flags.handle_debts')) {
+            Log::debug('handle_debts is disabled.');
+
+            return;
+        }
+        Log::error('TODO');
+
+        return;
+        Log::debug(sprintf('Now in %s', __METHOD__));
+        /** @var TransactionJournal $journal */
+        foreach ($this->group->transactionJournals as $journal) {
+            try {
+                $this->recalculateJournal($journal);
+            } catch (FireflyException $e) {
+                Log::error($e->getTraceAsString());
+                Log::error('Could not recalculate');
+            }
+        }
+        Log::debug(sprintf('Done with %s', __METHOD__));;
+    }
+
+    /**
+     * @param TransactionJournal $journal
+     *
+     * @throws FireflyException
+     */
+    private function recalculateJournal(TransactionJournal $journal): void
+    {
+        if (TransactionType::DEPOSIT !== $journal->transactionType->type) {
+            Log::debug('Journal is not a deposit.');
+
+            return;
+        }
+        $source      = $this->getSourceAccount($journal);
+        $destination = $this->getDestinationAccount($journal);
+        // destination must be liability, source must be expense.
+        if (AccountType::REVENUE !== $source->accountType->type) {
+            Log::debug('Source is not a revenue account.');
+
+            return;
+        }
+        if (!in_array($destination->accountType->type, config('firefly.valid_liabilities'))) {
+            Log::debug('Destination is not a liability.');
+
+            return;
+        }
+        $repository = app(AccountRepositoryInterface::class);
+        $repository->setUser($destination->user);
+        $direction = $repository->getMetaValue($destination, 'liability_direction');
+        if ('credit' !== $direction) {
+            Log::debug(sprintf('Destination liabiltiy direction is "%s", do nothing.', $direction));
+        }
+        /*
+         * This destination is a liability and an incoming debt. The amount paid into the liability changes the original debt amount.
+         *
+         */
+        Log::debug('Do something!');
+    }
+
+    /**
+     * @param TransactionJournal $journal
+     *
+     * @return Account
+     * @throws FireflyException
+     */
+    private function getSourceAccount(TransactionJournal $journal): Account
+    {
+        return $this->getAccount($journal, '<');
+    }
+
+    /**
+     * @param TransactionJournal $journal
+     *
+     * @return Account
+     * @throws FireflyException
+     */
+    private function getDestinationAccount(TransactionJournal $journal): Account
+    {
+        return $this->getAccount($journal, '>');
+    }
+
+    /**
+     * @param TransactionJournal $journal
+     * @param string             $direction
+     *
+     * @return Account
+     * @throws FireflyException
+     */
+    private function getAccount(TransactionJournal $journal, string $direction): Account
+    {
+        /** @var Transaction $transaction */
+        $transaction = $journal->transactions()->where('amount', $direction, '0')->first();
+        if (null === $transaction) {
+            throw new FireflyException(sprintf('Cannot find "%s"-transaction of journal #%d', $direction, $journal->id));
+        }
+        $account = $transaction->account;
+        if (null === $account) {
+            throw new FireflyException(sprintf('Cannot find "%s"-account of transaction #%d of journal #%d', $direction, $transaction->id, $journal->id));
+        }
+
+        return $account;
+    }
+
+    /**
+     * @param TransactionGroup $group
+     */
+    public function setGroup(TransactionGroup $group): void
+    {
+        $this->group = $group;
+    }
+
+
+}
\ No newline at end of file