Python for Small Business: Automate Your Invoicing and Payments

#python #automation #business #finance

Python for Small Business: Automate Your Invoicing

Manual invoicing wastes hours every month. Here is how to automate it with Python.

Generate PDF Invoices

from reportlab.lib.pagesizes import letter
from reportlab.pdfgen import canvas
from datetime import date

def generate_invoice(client, items, invoice_num):
    filename = "invoice_" + str(invoice_num) + ".pdf"
    c = canvas.Canvas(filename, pagesize=letter)

    c.setFont("Helvetica-Bold", 20)
    c.drawString(50, 750, "INVOICE")
    c.setFont("Helvetica", 12)
    c.drawString(50, 730, "Invoice #: " + str(invoice_num))
    c.drawString(50, 715, "Date: " + str(date.today()))
    c.drawString(50, 670, "Bill To: " + client['name'])
    c.drawString(50, 655, client['email'])

    y = 600
    total = 0
    for item in items:
        amount = item['qty'] * item['rate']
        total += amount
        c.drawString(50, y, item['description'])
        c.drawString(400, y, "$" + str(amount))
        y -= 20

    c.setFont("Helvetica-Bold", 14)
    c.drawString(350, y - 20, "TOTAL: $" + str(total))
    c.save()
    return filename

Send Invoice by Email

import smtplib
from email.mime.multipart import MIMEMultipart
from email.mime.base import MIMEBase
from email.mime.text import MIMEText
from email import encoders

def send_invoice(client_email, invoice_path, invoice_num):
    msg = MIMEMultipart()
    msg["Subject"] = "Invoice #" + str(invoice_num) + " - Payment Due in 30 Days"
    msg["From"] = "billing@yourcompany.com"
    msg["To"] = client_email
    msg.attach(MIMEText("Please find your invoice attached."))

    with open(invoice_path, "rb") as f:
        pdf = MIMEBase("application", "pdf")
        pdf.set_payload(f.read())
        encoders.encode_base64(pdf)
        pdf.add_header("Content-Disposition", "attachment; filename=invoice.pdf")
        msg.attach(pdf)

    with smtplib.SMTP("smtp.gmail.com", 587) as s:
        s.starttls()
        s.login("billing@yourcompany.com", "your-app-password")
        s.send_message(msg)

Track Overdue Invoices

import sqlite3
from datetime import date

def get_outstanding():
    conn = sqlite3.connect("invoices.db")
    conn.execute("CREATE TABLE IF NOT EXISTS invoices (id TEXT, client TEXT, amount REAL, due TEXT, paid INTEGER DEFAULT 0)")
    return conn.execute("SELECT * FROM invoices WHERE paid=0 ORDER BY due").fetchall()

def send_reminders():
    today = date.today()
    for invoice in get_outstanding():
        due = date.fromisoformat(invoice[3])
        days = (today - due).days
        if days > 0:
            print("Overdue by " + str(days) + " days: " + invoice[0])