I would say 30 days is more than enough.However, you can email them for invoice overdue.And open a ticket before terminating,whatever his invoice is $0.01 or $10, just open a ticket before terminating.That's all.

If you use WHMCS then you can set when the invoice is sent X days before due date

ours is set like this

An invoice will be generated and sent 14 days before the due date
A reminder will be sent 1 day before the due date
Invoice then resent on due date and then if unpaid
After 1 day a First Overdue reminder is sent.
After 2 days a Second Overdue reminder is sent.
After 2 days your account will be suspended and a 20% or £2 late fee is added to the invoice, whichever is greater.
After 3 days a Third and Final reminder is sent
After 14 Days your account will be terminated.

so basically from invoice being issued to account termination they have had had 28 days to pay the invoice or contact us

7 days after termination, if any invoices still remain unpaid, they will be passed onto Express Debt Collection and £5 fee added to the invoice

so they have already had 1 invoice and 5 reminder before termination, so why should i open a support ticket with the client before termination

Generally reminder should be sent about renewal in specific time interval, once the renewal date is expired. This can be set in your billing software as per the convention and even if after couple of reminder if client do not responds or unwilling to renew; you can terminate an account.

We give all our clients a max of 30 days before we terminate accounts. If clients work with us or are a high end client, we might extend this. This is how we do it.

Al invoices will be generated and sent 14 days before the due date

A reminder will be sent 1 day before the due date

After 1 day a First Overdue reminder is sent.

After 2 days a Second Overdue reminder is sent.

After 3 days your account will be suspended and a 10% fee is added to the invoice.

After 5 days a Third and Final reminder is sent.

After 30 Days, the account will be terminated, but a backup of the account will be made, that we hold for 60 days.

That is what Billing Software like WHMCS does, as we have it set up. i think 1 invoice and 5 reminders in a 28 day period is enough for a client to pay or contact you

We also have 30 days period on unpaid service, We send 1 invoice and 4 reminders through out the the 30 days. So yes I think it is fair.

We have the following policy:

New Clients
- You place an order, we expect an immediate payment within 24 hours. If the order is not paid for within 24 hours, your order is deleted and you are reported to Fraud Record as non-payment, as there is no reason why the order should not have been paid for within the 1st 24 hours.
- We delete your order and we ban the IP and close the account.

Existing Clients
- Invoices are sent 7 days before the due date.
- You are notified 1 week before your due date, giving you plenty of time to put money in your account.
- If you can't pay within those 7 days, then you need to contact us and let us know why and setup payment arrangements.
- If account is not paid by 11:59 PM ET on the 7th day, the system suspends the account and then adds a $25 late fee to the invoice.
- The client is given an additional 21 days to pay the invoice. If they don't pay it by the end of the 30 days, their service is terminated and all other services that they have with us are 'suspended' manually, which usually forces the client to get in contact with us.
- If they want to continue services, the account must be paid up to day, plus an additional $25 administrative / reconnect fee, in addition to the $25 late fee that is already on the invoice.
- A report is filed with Fraud Record to document this and to alert others about this client.
- If the client doesn't contact us within 7 days, then we terminate all services and we close the customer's account and ban their IP.
- If their account is terminate, we do not keep backups of their accounts and will not restore their account.

No one likes non-pays, simply put.

3 days to suspend, 15 days to terminate

I would say to generate the invoice with 5 days before it is due. After it is due, leave it maximum 3 days until you suspend. After you suspend, keep the account for at least 30 days before deleting the data in case the customer returns. If space is not a problem for you, increase the recovery period up to 6 months. We had lots of customers that came back after even 4 months.