diff --git a/src/components/BalanceAssertionEditor.vue b/src/components/BalanceAssertionEditor.vue
new file mode 100644
index 0000000..bf074d9
--- /dev/null
+++ b/src/components/BalanceAssertionEditor.vue
@@ -0,0 +1,117 @@
+<!--
+	DrCr: Web-based double-entry bookkeeping framework
+	Copyright (C) 2022–2024  Lee Yingtong Li (RunasSudo)
+	
+	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/>.
+-->
+
+<template>
+	<div class="grid grid-cols-[max-content_1fr] space-y-2 mb-4 items-baseline">
+		<label for="dt" class="block text-gray-900 pr-4">Date</label>
+		<div>
+			<input type="date" class="bordered-field" id="dt" v-model="assertion.dt">
+		</div>
+		<label for="description" class="block text-gray-900 pr-4">Description</label>
+		<div>
+			<input type="text" class="bordered-field" id="description" v-model="assertion.description" placeholder=" ">
+		</div>
+		<label for="account" class="block text-gray-900 pr-4">Account</label>
+		<div class="relative combobox">
+			<input type="text" class="bordered-field peer" id="account" v-model="assertion.account" placeholder=" " autocomplete="off">
+			<!--{% include 'components/accounts_combobox_inner.html' %}-->
+		</div>
+		<label for="amount" class="block text-gray-900 pr-4">Balance</label>
+		<div class="relative shadow-sm">
+			<div class="pointer-events-none absolute inset-y-0 left-0 flex items-center pl-3">
+				<span class="text-gray-500">{{ db.metadata.reporting_commodity }}</span>
+			</div>
+			<!-- TODO: Display existing credit assertion as credit, not as negative debit -->
+			<input type="number" class="bordered-field pl-7 pr-16" step="0.01" v-model="assertion.amount_abs" placeholder="0.00">
+			<div class="absolute inset-y-0 right-0 flex items-center">
+				<select class="h-full border-0 bg-transparent py-0 pl-2 pr-8 text-gray-900 focus:ring-2 focus:ring-inset focus:ring-indigo-600" v-model="assertion.sign">
+					<option value="dr">Dr</option>
+					<option value="cr">Cr</option>
+				</select>
+			</div>
+		</div>
+	</div>
+	
+	<div class="flex justify-end mt-4 space-x-2">
+		<button class="btn-secondary text-red-600 ring-red-500" @click="deleteAssertion" v-if="assertion.id !== null">Delete</button>
+		<button class="btn-primary" @click="saveAssertion">Save</button>
+	</div>
+</template>
+
+<script setup lang="ts">
+	import dayjs from 'dayjs';
+	
+	import { getCurrentWindow } from '@tauri-apps/api/window';
+	
+	import { defineProps } from 'vue';
+	
+	import { DT_FORMAT, db, deserialiseAmount } from '../db.ts';
+	
+	export interface EditingAssertion {
+		id: number | null,
+		dt: string,
+		description: string,
+		account: string,
+		sign: string,
+		amount_abs: string,
+	}
+	
+	const { assertion } = defineProps<{ assertion: EditingAssertion }>();
+	
+	async function saveAssertion() {
+		// Save changes to the assertion
+		const amount_abs = deserialiseAmount('' + assertion.amount_abs);
+		const quantity = assertion.sign === 'dr' ? amount_abs.quantity : -amount_abs.quantity;
+		
+		const session = await db.load();
+		
+		if (assertion.id === null) {
+			await session.execute(
+				`INSERT INTO balance_assertions (dt, description, account, quantity, commodity)
+				VALUES ($1, $2, $3, $4, $5)`,
+				[dayjs(assertion.dt).format(DT_FORMAT), assertion.description, assertion.account, quantity, amount_abs.commodity]
+			);
+		} else {
+			await session.execute(
+				`UPDATE balance_assertions
+				SET dt = $1, description = $2, account = $3, quantity = $4, commodity = $5
+				WHERE id = $6`,
+				[dayjs(assertion.dt).format(DT_FORMAT), assertion.description, assertion.account, quantity, amount_abs.commodity, assertion.id]
+			);
+		}
+		
+		await getCurrentWindow().close();
+	}
+	
+	async function deleteAssertion() {
+		// Delete the current assertion
+		if (!await confirm('Are you sure you want to delete this balance assertion? This operation is irreversible.')) {
+			return;
+		}
+		
+		const session = await db.load();
+		
+		await session.execute(
+			`DELETE FROM balance_assertions
+			WHERE id = $1`,
+			[assertion.id]
+		);
+		
+		await getCurrentWindow().close();
+	}
+</script>
diff --git a/src/main.ts b/src/main.ts
index 824f9fb..d0c32a1 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -31,6 +31,8 @@ async function initApp() {
 	const routes = [
 		{ path: '/', name: 'index', component: () => import('./pages/HomeView.vue') },
 		{ path: '/balance-assertions', name: 'balance-assertions', component: () => import('./pages/BalanceAssertionsView.vue') },
+		{ path: '/balance-assertions/edit/:id', name: 'balance-assertions-edit', component: () => import('./pages/EditBalanceAssertionView.vue') },
+		{ path: '/balance-assertions/new', name: 'balance-assertions-new', component: () => import('./pages/NewBalanceAssertionView.vue') },
 		{ path: '/chart-of-accounts', name: 'chart-of-accounts', component: () => import('./pages/ChartOfAccountsView.vue') },
 		{ path: '/general-ledger', name: 'general-ledger', component: () => import('./pages/GeneralLedgerView.vue') },
 		{ path: '/journal', name: 'journal', component: () => import('./pages/JournalView.vue') },
diff --git a/src/pages/BalanceAssertionsView.vue b/src/pages/BalanceAssertionsView.vue
index 5343bc3..eb2ae56 100644
--- a/src/pages/BalanceAssertionsView.vue
+++ b/src/pages/BalanceAssertionsView.vue
@@ -22,12 +22,10 @@
 	</h1>
 	
 	<div class="my-4 flex gap-x-2">
-		<!--<a href="{{ url_for('balance_assertions_new') }}" class="btn-primary pl-2">
-			<svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-4 h-4">
-				<path stroke-linecap="round" stroke-linejoin="round" d="M12 4.5v15m7.5-7.5h-15" />
-			</svg>
+		<a href="/balance-assertions/new" class="btn-primary pl-2" onclick="return openLinkInNewWindow(this);">
+			<PlusIcon class="w-4 h-4" />
 			New assertion
-		</a>-->
+		</a>
 	</div>
 	
 	<table class="min-w-full">
@@ -54,10 +52,8 @@
 					<XMarkIcon class="w-4 h-4 text-red-500" v-if="!assertion.isValid" />
 				</td>
 				<td class="py-0.5 pl-1 text-gray-900 text-end">
-					<a href="#" class="text-gray-500 hover:text-gray-700">
-						<svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-4 h-4 inline align-middle -mt-0.5">
-							<path stroke-linecap="round" stroke-linejoin="round" d="m16.862 4.487 1.687-1.688a1.875 1.875 0 1 1 2.652 2.652L6.832 19.82a4.5 4.5 0 0 1-1.897 1.13l-2.685.8.8-2.685a4.5 4.5 0 0 1 1.13-1.897L16.863 4.487Zm0 0L19.5 7.125" />
-						</svg>
+					<a :href="'/balance-assertions/edit/' + assertion.id" class="text-gray-500 hover:text-gray-700" onclick="return openLinkInNewWindow(this);">
+						<PencilIcon class="w-4 h-4" />
 					</a>
 				</td>
 			</tr>
@@ -72,7 +68,8 @@
 	
 	import { db, totalBalancesAtDate } from '../db.ts';
 	import { pp } from '../display.ts';
-	import { CheckIcon, XMarkIcon } from '@heroicons/vue/24/outline';
+	import { CheckIcon, PencilIcon, XMarkIcon } from '@heroicons/vue/24/outline';
+	import { PlusIcon } from '@heroicons/vue/16/solid';
 	
 	const balanceAssertions = ref([] as ValidatedBalanceAssertion[]);
 	
diff --git a/src/pages/EditBalanceAssertionView.vue b/src/pages/EditBalanceAssertionView.vue
new file mode 100644
index 0000000..e7df81e
--- /dev/null
+++ b/src/pages/EditBalanceAssertionView.vue
@@ -0,0 +1,67 @@
+<!--
+	DrCr: Web-based double-entry bookkeeping framework
+	Copyright (C) 2022–2024  Lee Yingtong Li (RunasSudo)
+	
+	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/>.
+-->
+
+<template>
+	<h1 class="page-heading mb-4">
+		Edit balance assertion
+	</h1>
+	
+	<BalanceAssertionEditor :assertion="assertion" />
+</template>
+
+<script setup lang="ts">
+	import dayjs from 'dayjs';
+	
+	import { ref } from 'vue';
+	import { useRoute } from 'vue-router';
+	
+	import { db, serialiseAmount } from '../db.ts';
+	import BalanceAssertionEditor, { EditingAssertion } from '../components/BalanceAssertionEditor.vue';
+	
+	const route = useRoute();
+	
+	const assertion = ref({
+		id: null,
+		dt: null!,
+		description: null!,
+		account: null!,
+		sign: null!,
+		amount_abs: null!,
+	} as EditingAssertion);
+	
+	async function load() {
+		const session = await db.load();
+		
+		const rawAssertions: any[] = await session.select(
+			`SELECT *
+			FROM balance_assertions
+			WHERE id = $1`,
+			[route.params.id]
+		);
+		const rawAssertion = rawAssertions[0];
+		
+		// Format parameters for display
+		rawAssertion.dt = dayjs(rawAssertion.dt).format('YYYY-MM-DD');
+		rawAssertion.sign = rawAssertion.quantity >= 0 ? 'dr' : 'cr';
+		rawAssertion.amount_abs = serialiseAmount(Math.abs(rawAssertion.quantity), rawAssertion.commodity);
+		
+		assertion.value = rawAssertion as EditingAssertion;
+	}
+	
+	load();
+</script>
diff --git a/src/pages/EditTransactionView.vue b/src/pages/EditTransactionView.vue
index b70aa0e..c4f1272 100644
--- a/src/pages/EditTransactionView.vue
+++ b/src/pages/EditTransactionView.vue
@@ -30,7 +30,7 @@
 	import { ref } from 'vue';
 	import { useRoute } from 'vue-router';
 	
-	import { JoinedTransactionPosting, Posting, db, joinedToTransactions, serialiseAmount } from '../db.ts';
+	import { JoinedTransactionPosting, db, joinedToTransactions, serialiseAmount } from '../db.ts';
 	import TransactionEditor, { EditingTransaction } from '../components/TransactionEditor.vue';
 	
 	const route = useRoute();
@@ -56,16 +56,18 @@
 		
 		const transactions = joinedToTransactions(joinedTransactionPostings);
 		if (transactions.length !== 1) { throw new Error('Unexpected number of transactions returned from SQL'); }
-		transaction.value = transactions[0] as unknown as EditingTransaction;
+		const rawTransaction = transactions[0] as any;
 		
 		// Format dt
-		transaction.value.dt = dayjs(transaction.value.dt).format('YYYY-MM-DD')
+		rawTransaction.dt = dayjs(rawTransaction.dt).format('YYYY-MM-DD');
 		
 		// Initialise sign and amount_abs
-		for (const posting of transaction.value.postings) {
-			posting.sign = (posting as unknown as Posting).quantity! >= 0 ? 'dr' : 'cr';
-			posting.amount_abs = serialiseAmount(Math.abs((posting as unknown as Posting).quantity), (posting as unknown as Posting).commodity);
+		for (const posting of rawTransaction.postings) {
+			posting.sign = posting.quantity >= 0 ? 'dr' : 'cr';
+			posting.amount_abs = serialiseAmount(Math.abs(posting.quantity), posting.commodity);
 		}
+		
+		transaction.value = rawTransaction as EditingTransaction;
 	}
 	load();
 </script>
diff --git a/src/pages/NewBalanceAssertionView.vue b/src/pages/NewBalanceAssertionView.vue
new file mode 100644
index 0000000..f02930d
--- /dev/null
+++ b/src/pages/NewBalanceAssertionView.vue
@@ -0,0 +1,41 @@
+<!--
+	DrCr: Web-based double-entry bookkeeping framework
+	Copyright (C) 2022–2024  Lee Yingtong Li (RunasSudo)
+	
+	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/>.
+-->
+
+<template>
+	<h1 class="page-heading mb-4">
+		New balance assertion
+	</h1>
+	
+	<BalanceAssertionEditor :assertion="assertion" />
+</template>
+
+<script setup lang="ts">
+	import dayjs from 'dayjs';
+	import { ref } from 'vue';
+	
+	import BalanceAssertionEditor, { EditingAssertion } from '../components/BalanceAssertionEditor.vue';
+	
+	const assertion = ref({
+		id: null,
+		dt: dayjs().format('YYYY-MM-DD'),
+		description: '',
+		account: '',
+		sign: 'dr',
+		amount_abs: '',
+	} as EditingAssertion);
+</script>