Process on the First Day of Every Month

cron expression AWS

$ cron(0 0 1 * ? *)

→

Once a month on the first day at midnight

cron(0

Minute

Hour

Day of Month

Month

Day of Week

Year

* In a Nutshell

The cron expression cron(0 0 1 * ? *) runs Once a month on the first day at midnight. Running tasks at the start of the month is crucial for processes like monthly billing cycles, generating periodic financial reports, or kicking off batch jobs that depend on a clean monthly slate. Failure to execute reliably can lead to manual interventions, data discrepancies, and delayed critical business operations.

* When to use this

Use cron(0 0 1 * ? *) when a recurring task needs to run Once a month on the first day at midnight. This schedule is commonly associated with financial processing and monthly schedules and report generation workloads. It uses AWS EventBridge (6 Fields) syntax, supported by Unix cron daemons, cloud schedulers such as AWS EventBridge, and container orchestration platforms such as Kubernetes CronJob.

CronBase parses cron(0 0 1 * ? *) using a dialect-aware rules engine that identifies the AWS EventBridge (6 Fields) format, validates field structure against the AWS EventBridge (6 Fields) specification, and produces the translation above. Next run times are calculated by forward-scanning from the current UTC clock. Learn how CronBase works.

Platform Implementations

Bash

Prerequisites

Unix/Linux host with a cron daemon running (vixie-cron, cronie, or systemd-cron). The script at /usr/local/bin/run-task.sh must exist and be executable (chmod +x).

Configuration

Run crontab -e to open the crontab editor. Cron reads the server's local timezone; prefix with CRON_TZ=UTC before the expression to pin to UTC. Always redirect output with >> /var/log/cron-tasks.log 2>&1 to capture both stdout and stderr.

Gotchas

Cron jobs inherit a minimal PATH — use full binary paths or set PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin at the top of the crontab. For sub-hourly schedules, add flock -n /tmp/run-task.lock before the command to skip overlapping runs if the previous execution is still running.

bash

# Add to crontab with: crontab -e
cron(0 0 1 * * /usr/local/bin/run-task.sh >> /var/log/cron-tasks.log 2>&1

Last verified: April 11, 2026

Nodejs

Prerequisites

Node.js 18+ with node-cron installed (npm install node-cron). Add "type": "module" to package.json to use the import syntax shown above.

Configuration

Pass { timezone: 'UTC' } as the third argument to cron.schedule(). Without this option the schedule uses the Node.js process timezone, which shifts during DST transitions when servers are not pinned to UTC.

Gotchas

node-cron uses standard 5-field cron syntax — not Quartz 6-field. If your job runs longer than the schedule interval the next trigger fires while the previous is still executing. Use a boolean guard or a queue to skip concurrent runs rather than relying on the scheduler to enforce it.

nodejs

import cron from 'node-cron';

cron.schedule('cron(0 0 1 * *', async () => {
  console.log('[cron] running at', new Date().toISOString());
  // your task logic here
}, { timezone: 'UTC' });

Last verified: April 11, 2026

Python

Prerequisites

Python 3.8+ with apscheduler installed (pip install apscheduler). For Python 3.12+ use apscheduler>=3.10.

Configuration

CronTrigger.from_crontab() accepts a standard 5-field cron string. Always pass timezone='UTC' to both the BlockingScheduler constructor and the trigger to ensure consistent scheduling regardless of the server's locale.

Gotchas

BlockingScheduler.start() blocks the calling thread indefinitely. For a web application, use BackgroundScheduler instead and call scheduler.start() at application startup. APScheduler logs missed fires if the process is stopped and restarted — configure misfire_grace_time (in seconds) to control how late a missed job is allowed to run.

python

from apscheduler.schedulers.blocking import BlockingScheduler
from apscheduler.triggers.cron import CronTrigger

scheduler = BlockingScheduler(timezone='UTC')

@scheduler.scheduled_job(
    CronTrigger.from_crontab('cron(0 0 1 * *', timezone='UTC')
)
def run_task() -> None:
    print('task running')
    # your task logic here

scheduler.start()

Last verified: April 11, 2026

Golang

Prerequisites

Go 1.18+ and github.com/robfig/cron/v3 (go get github.com/robfig/cron/v3).

Configuration

Always create the scheduler with cron.New(cron.WithLocation(time.UTC)). Without WithLocation, the library defaults to the server's local timezone. Call c.Start() to begin the scheduler, then block with select {} to keep the process alive.

Gotchas

robfig/cron v3 uses standard 5-field cron expressions by default. To add second-level precision (6 fields), pass cron.WithSeconds() to cron.New() — but this changes field positions, so never mix syntaxes in the same scheduler. Always check the error returned by c.AddFunc() — a malformed expression is silently ignored without it.

golang

package main

import (
	"fmt"
	"time"

	"github.com/robfig/cron/v3"
)

func main() {
	c := cron.New(cron.WithLocation(time.UTC))
	_, err := c.AddFunc("cron(0 0 1 * *", func() {
		fmt.Println("task running at", time.Now().UTC())
		// your task logic here
	})
	if err != nil {
		panic(err)
	}
	c.Start()
	defer c.Stop()
	select {}
}

Last verified: April 11, 2026

Java

Prerequisites

Spring Boot 2.7+ (or Spring Framework 5.3+) with spring-context on the classpath. Annotate your @SpringBootApplication class with @EnableScheduling — without it, @Scheduled methods are silently ignored.

Configuration

Spring @Scheduled uses a 6-field Quartz-style expression: [sec] [min] [hr] [dom] [mon] [dow]. The expression 0 cron(0 0 1 * ? is derived from cron(0 0 1 * ? *) — a leading 0 is prepended for the seconds field, and ? replaces the unconstrained day field.

Gotchas

Standard Unix cron has 5 fields; Spring requires 6. Pasting a 5-field expression directly into @Scheduled shifts every field by one and the job misfires silently. Use ? for either dom or dow — Quartz does not allow both to be *.

java

import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

@Component
public class ScheduledTask {

    @Scheduled(cron = "0 cron(0 0 1 * ?")
    public void runTask() {
        System.out.println("task running at: " + java.time.Instant.now());
        // your task logic here
    }
}

Last verified: April 11, 2026

Kubernetes

Prerequisites

Kubernetes 1.21+ (CronJob API is GA). kubectl configured with cluster access. Container image must be pullable from within the cluster.

Configuration

Apply with kubectl apply -f cronjob.yaml. Check status with kubectl get cronjobs and inspect run history with kubectl get jobs. concurrencyPolicy: Allow is set because this schedule fires infrequently — parallel runs are acceptable.

Gotchas

Without startingDeadlineSeconds, a missed job (e.g., due to cluster downtime) triggers as soon as the controller recovers. Kubernetes 1.25+ supports timeZone: UTC in the spec to avoid timezone ambiguity. Keep successfulJobsHistoryLimit and failedJobsHistoryLimit low to avoid accumulating stale Job objects in the cluster.

kubernetes

apiVersion: batch/v1
kind: CronJob
metadata:
  name: scheduled-task
spec:
  schedule: "cron(0 0 1 * *"
  concurrencyPolicy: Allow
  jobTemplate:
    spec:
      template:
        spec:
          restartPolicy: OnFailure
          containers:
          - name: task
            image: alpine:3.19
            command: ["/bin/sh", "-c", "echo 'task running'"]

Last verified: April 11, 2026

Frequently Asked Questions

What specific action does this cron expression trigger?

This cron expression is configured to trigger a specific action precisely at midnight on the very first day of each calendar month. It ensures that time-sensitive monthly tasks commence at the earliest possible moment.

How does this schedule handle time zone changes and daylight saving time?

The execution time is based on the configured time zone of the scheduler. It will adjust automatically for daylight saving time transitions to ensure it runs at the intended local time of midnight on the first of the month.

How can I verify that my scheduled task is running correctly?

You can verify the successful execution by checking the logs for the specific task that is scheduled to run. Look for timestamps corresponding to midnight on the first day of each month, confirming the job completed its intended run.

Are there any common pitfalls or unexpected behaviors with this schedule?

A key consideration is that jobs scheduled for the first of the month might coincide with other end-of-month or start-of-month processes, potentially increasing resource contention or creating race conditions if not managed carefully.

What is a common variation or alternative for this monthly schedule?

A common variation is to run tasks at a different time of day on the first of the month, such as early morning after initial system checks, or to schedule it for the last day of the previous month for specific reporting needs.