diff --git a/packages/loot-core/src/mocks/budget.ts b/packages/loot-core/src/mocks/budget.ts
index 8c308b3393d..308b64f17ef 100644
--- a/packages/loot-core/src/mocks/budget.ts
+++ b/packages/loot-core/src/mocks/budget.ts
@@ -12,24 +12,26 @@ import q from '../shared/query';
 import type {
   CategoryGroupEntity,
   PayeeEntity,
-  TransactionEntity,
+  NewTransactionEntity,
 } from '../types/models';
 
 import random from './random';
 
-function pickRandom(list) {
+type MockPayeeEntity = PayeeEntity & { bill?: boolean };
+
+function pickRandom<T>(list: T[]): T {
   return list[Math.floor(random() * list.length) % list.length];
 }
 
-function number(start, end) {
+function number(start: number, end: number) {
   return start + (end - start) * random();
 }
 
-function integer(start, end) {
+function integer(start: number, end: number) {
   return Math.round(number(start, end));
 }
 
-function findMin(items, field) {
+function findMin<T, K extends keyof T>(items: T[], field: K) {
   let item = items[0];
   for (let i = 0; i < items.length; i++) {
     if (items[i][field] < item[field]) {
@@ -39,17 +41,20 @@ function findMin(items, field) {
   return item;
 }
 
-function getStartingBalanceCat(categories) {
+function getStartingBalanceCat(categories: CategoryGroupEntity[]) {
   return categories.find(c => c.name === 'Starting Balances').id;
 }
 
-function extractCommonThings(payees, groups) {
+function extractCommonThings(
+  payees: MockPayeeEntity[],
+  groups: CategoryGroupEntity[],
+) {
   const incomePayee = payees.find(p => p.name === 'Deposit');
   const expensePayees = payees.filter(
     p => p.name !== 'Deposit' && p.name !== 'Starting Balance',
   );
-  const expenseGroup = groups.find(g => g.is_income === 0);
-  const incomeGroup = groups.find(g => g.is_income === 1);
+  const expenseGroup = groups.find(g => !g.is_income);
+  const incomeGroup = groups.find(g => g.is_income);
   const categories = expenseGroup.categories.filter(
     c =>
       [
@@ -73,7 +78,12 @@ function extractCommonThings(payees, groups) {
   };
 }
 
-async function fillPrimaryChecking(handlers, account, payees, groups) {
+async function fillPrimaryChecking(
+  handlers,
+  account,
+  payees: MockPayeeEntity[],
+  groups: CategoryGroupEntity[],
+) {
   const {
     incomePayee,
     expensePayees,
@@ -107,7 +117,7 @@ async function fillPrimaryChecking(handlers, account, payees, groups) {
       amount = integer(0, random() < 0.05 ? -8000 : -700);
     }
 
-    const transaction: TransactionEntity = {
+    const transaction: NewTransactionEntity = {
       amount,
       payee: payee.id,
       account: account.id,
@@ -129,7 +139,7 @@ async function fillPrimaryChecking(handlers, account, payees, groups) {
           amount: transaction.amount - a * 2,
           category: pick(),
         },
-      ] as TransactionEntity[];
+      ];
     }
   }
 
@@ -391,7 +401,7 @@ async function fillOther(handlers, account, payees, groups) {
   const numTransactions = integer(3, 6);
   const category = incomeGroup.categories.find(c => c.name === 'Income');
 
-  const transactions: TransactionEntity[] = [
+  const transactions: NewTransactionEntity[] = [
     {
       amount: integer(3250, 3700) * 100 * 100,
       payee: payees.find(p => p.name === 'Starting Balance').id,
@@ -585,7 +595,7 @@ export async function createTestBudget(handlers) {
     }),
   );
 
-  const payees: Array<PayeeEntity & { bill?: boolean }> = [
+  const payees: Array<MockPayeeEntity> = [
     { name: 'Starting Balance' },
     { name: 'Kroger' },
     { name: 'Publix' },
diff --git a/packages/loot-core/src/server/accounts/transaction-rules.ts b/packages/loot-core/src/server/accounts/transaction-rules.ts
index 4761375a32a..3cb418afce7 100644
--- a/packages/loot-core/src/server/accounts/transaction-rules.ts
+++ b/packages/loot-core/src/server/accounts/transaction-rules.ts
@@ -11,7 +11,11 @@ import {
   getApproxNumberThreshold,
 } from '../../shared/rules';
 import { partitionByField, fastSetMerge } from '../../shared/util';
-import { type RuleActionEntity, type RuleEntity } from '../../types/models';
+import {
+  type TransactionEntity,
+  type RuleActionEntity,
+  type RuleEntity,
+} from '../../types/models';
 import { schemaConfig } from '../aql';
 import * as db from '../db';
 import { getMappings } from '../db/mappings';
@@ -682,7 +686,7 @@ export async function updateCategoryRules(transactions) {
 
   // Also look 180 days in the future to get any future transactions
   // (this might change when we think about scheduled transactions)
-  let register = await db.all(
+  let register: TransactionEntity[] = await db.all(
     `SELECT t.* FROM v_transactions t
      LEFT JOIN accounts a ON a.id = t.account
      WHERE date >= ? AND date <= ? AND is_parent = 0 AND a.closed = 0
diff --git a/packages/loot-core/src/shared/transactions.ts b/packages/loot-core/src/shared/transactions.ts
index 5e99b43d4fb..d12fd0768eb 100644
--- a/packages/loot-core/src/shared/transactions.ts
+++ b/packages/loot-core/src/shared/transactions.ts
@@ -1,5 +1,7 @@
 import { v4 as uuidv4 } from 'uuid';
 
+import { type TransactionEntity } from '../types/models';
+
 import { last, diffItems, applyChanges } from './util';
 
 export function isPreviewId(id) {
@@ -80,8 +82,8 @@ function getSplit(transactions, parentIndex) {
   return split;
 }
 
-export function ungroupTransactions(transactions) {
-  const x = transactions.reduce((list, parent) => {
+export function ungroupTransactions(transactions: TransactionEntity[]) {
+  return transactions.reduce<TransactionEntity[]>((list, parent) => {
     const { subtransactions, ...trans } = parent;
     const _subtransactions = subtransactions || [];
 
@@ -92,25 +94,31 @@ export function ungroupTransactions(transactions) {
     }
     return list;
   }, []);
-  return x;
 }
 
 function groupTransaction(split) {
   return { ...split[0], subtransactions: split.slice(1) };
 }
 
-export function ungroupTransaction(split) {
+export function ungroupTransaction(split: TransactionEntity | null) {
   if (split == null) {
     return null;
   }
   return ungroupTransactions([split]);
 }
 
-export function applyTransactionDiff(groupedTrans, diff) {
+export function applyTransactionDiff(
+  groupedTrans: Parameters<typeof ungroupTransaction>[0],
+  diff: Parameters<typeof applyChanges>[0],
+) {
   return groupTransaction(applyChanges(diff, ungroupTransaction(groupedTrans)));
 }
 
-function replaceTransactions(transactions, id, func) {
+function replaceTransactions(
+  transactions: TransactionEntity[],
+  id: string,
+  func: (transaction: TransactionEntity) => TransactionEntity,
+) {
   const idx = transactions.findIndex(t => t.id === id);
   const trans = transactions[idx];
   const transactionsCopy = [...transactions];
@@ -127,7 +135,9 @@ function replaceTransactions(transactions, id, func) {
     }
 
     const split = getSplit(transactions, parentIndex);
-    let grouped = func(groupTransaction(split));
+    let grouped: TransactionEntity | { id: string; _deleted: boolean } = func(
+      groupTransaction(split),
+    );
     const newSplit = ungroupTransaction(grouped);
 
     let diff;
@@ -159,7 +169,10 @@ function replaceTransactions(transactions, id, func) {
   }
 }
 
-export function addSplitTransaction(transactions, id) {
+export function addSplitTransaction(
+  transactions: TransactionEntity[],
+  id: string,
+) {
   return replaceTransactions(transactions, id, trans => {
     if (!trans.is_parent) {
       return trans;
diff --git a/packages/loot-core/src/shared/util.ts b/packages/loot-core/src/shared/util.ts
index cf587db47ec..3c32ab5cd70 100644
--- a/packages/loot-core/src/shared/util.ts
+++ b/packages/loot-core/src/shared/util.ts
@@ -1,4 +1,4 @@
-export function last(arr) {
+export function last<T>(arr: Array<T>) {
   return arr[arr.length - 1];
 }
 
@@ -33,7 +33,14 @@ export function hasFieldsChanged(obj1, obj2, fields) {
   return changed;
 }
 
-export function applyChanges(changes, items) {
+export function applyChanges<T extends { id: string }>(
+  changes: {
+    added?: T[];
+    updated?: T[];
+    deleted?: T[];
+  },
+  items: T[],
+) {
   items = [...items];
 
   if (changes.added) {
@@ -64,7 +71,7 @@ export function applyChanges(changes, items) {
   return items;
 }
 
-export function partitionByField(data, field) {
+export function partitionByField<T, K extends keyof T>(data: T[], field: K) {
   const res = new Map();
   for (let i = 0; i < data.length; i++) {
     const item = data[i];
@@ -93,7 +100,7 @@ export function groupBy<T, K extends keyof T>(data: T[], field: K) {
 // `Map` is better, but we can't swap it out because `Map` has a
 // different API and we need to go through and update everywhere that
 // uses it.
-function _groupById(data) {
+function _groupById<T extends { id: string }>(data: T[]) {
   const res = new Map();
   for (let i = 0; i < data.length; i++) {
     const item = data[i];
@@ -102,7 +109,7 @@ function _groupById(data) {
   return res;
 }
 
-export function diffItems(items, newItems) {
+export function diffItems<T extends { id: string }>(items: T[], newItems: T[]) {
   const grouped = _groupById(items);
   const newGrouped = _groupById(newItems);
   const added = [];
@@ -127,7 +134,7 @@ export function diffItems(items, newItems) {
   return { added, updated, deleted };
 }
 
-export function groupById(data) {
+export function groupById<T extends { id: string }>(data: T[]) {
   const res = {};
   for (let i = 0; i < data.length; i++) {
     const item = data[i];
@@ -168,7 +175,7 @@ export function getIn(map, keys) {
   return item;
 }
 
-export function fastSetMerge(set1, set2) {
+export function fastSetMerge<T>(set1: Set<T>, set2: Set<T>) {
   const finalSet = new Set(set1);
   const iter = set2.values();
   let value = iter.next();
@@ -214,7 +221,13 @@ export function setNumberFormat(config: typeof numberFormatConfig) {
   numberFormatConfig = config;
 }
 
-export function getNumberFormat({ format, hideFraction } = numberFormatConfig) {
+export function getNumberFormat({
+  format,
+  hideFraction,
+}: {
+  format: NumberFormats;
+  hideFraction: boolean;
+} = numberFormatConfig) {
   let locale, regex, separator;
 
   switch (format) {
@@ -282,11 +295,14 @@ export function safeNumber(value: number) {
   return value;
 }
 
-export function toRelaxedNumber(value) {
+export function toRelaxedNumber(value: string) {
   return integerToAmount(currencyToInteger(value) || 0);
 }
 
-export function integerToCurrency(n, formatter = getNumberFormat().formatter) {
+export function integerToCurrency(
+  n: number,
+  formatter = getNumberFormat().formatter,
+) {
   return formatter.format(safeNumber(n) / 100);
 }
 
@@ -294,7 +310,7 @@ export function amountToCurrency(n) {
   return getNumberFormat().formatter.format(n);
 }
 
-export function currencyToAmount(str) {
+export function currencyToAmount(str: string) {
   const amount = parseFloat(
     str
       .replace(getNumberFormat().regex, '')
@@ -303,12 +319,12 @@ export function currencyToAmount(str) {
   return isNaN(amount) ? null : amount;
 }
 
-export function currencyToInteger(str) {
+export function currencyToInteger(str: string) {
   const amount = currencyToAmount(str);
   return amount == null ? null : amountToInteger(amount);
 }
 
-export function stringToInteger(str) {
+export function stringToInteger(str: string) {
   const amount = parseInt(str.replace(/[^-0-9.,]/g, ''));
   if (!isNaN(amount)) {
     return amount;
@@ -316,7 +332,7 @@ export function stringToInteger(str) {
   return null;
 }
 
-export function amountToInteger(n) {
+export function amountToInteger(n: number) {
   return Math.round(n * 100);
 }
 
@@ -328,12 +344,12 @@ export function integerToAmount(n) {
 // financial files and we don't want to parse based on the user's
 // number format, because the user could be importing from many
 // currencies. We extract out the numbers and just ignore separators.
-export function looselyParseAmount(amount) {
-  function safeNumber(v) {
+export function looselyParseAmount(amount: string) {
+  function safeNumber(v: number): null | number {
     return isNaN(v) ? null : v;
   }
 
-  function extractNumbers(v) {
+  function extractNumbers(v: string): string {
     return v.replace(/[^0-9-]/g, '');
   }
 
diff --git a/packages/loot-core/src/types/models/transaction.d.ts b/packages/loot-core/src/types/models/transaction.d.ts
index 3687db05082..07a64a23175 100644
--- a/packages/loot-core/src/types/models/transaction.d.ts
+++ b/packages/loot-core/src/types/models/transaction.d.ts
@@ -3,15 +3,14 @@ import type { CategoryEntity } from './category';
 import type { PayeeEntity } from './payee';
 import type { ScheduleEntity } from './schedule';
 
-export interface TransactionEntity {
-  id?: string;
+export interface NewTransactionEntity {
   is_parent?: boolean;
   is_child?: boolean;
   parent_id?: string;
-  account: AccountEntity;
-  category?: CategoryEntity;
+  account: string;
+  category?: string;
   amount: number;
-  payee?: PayeeEntity;
+  payee?: string;
   notes?: string;
   date: string;
   imported_id?: string;
@@ -22,6 +21,15 @@ export interface TransactionEntity {
   cleared?: boolean;
   reconciled?: boolean;
   tombstone?: boolean;
+  schedule?: string;
+  subtransactions?: Omit<NewTransactionEntity, 'account' | 'date'>[];
+}
+
+export interface TransactionEntity extends NewTransactionEntity {
+  id: string;
+  account: AccountEntity;
+  category?: CategoryEntity;
+  payee?: PayeeEntity;
   schedule?: ScheduleEntity;
   subtransactions?: TransactionEntity[];
 }
diff --git a/upcoming-release-notes/2023.md b/upcoming-release-notes/2023.md
new file mode 100644
index 00000000000..d75b90fdac5
--- /dev/null
+++ b/upcoming-release-notes/2023.md
@@ -0,0 +1,6 @@
+---
+category: Maintenance
+authors: [MatissJanis]
+---
+
+Added more strict typings to `utils.ts` and some of its dependencies