September 28 2026

How to Combine Multiple ConnectWise Invoices Into One

Overview

Most MSPs end up with several invoices per client each month: the agreement invoice, a project or sales order invoice, a few standard invoices for one-off work. Your accounting team wants them separate. Your clients want one document with one total.

ConnectWise PSA doesn’t combine invoices on its own, but you can do it with a custom invoice template. In this post I’ll go over the two ways a combined invoice can look, three ways to decide which invoices get combined, and the problems we’ve run into building these for clients, so you can avoid them whether you build your own or have us do it.

Two Ways to Combine

Before anything else, decide what the client should see.

Merged: the line items from every invoice are pulled into one invoice with one set of totals. This reads like a single monthly statement, and it’s what most clients mean when they ask for “one invoice.”
Collated: each invoice keeps its own pages and totals, and they’re packaged into one PDF with a combined total up front. This works better when the client’s AP team matches payments to individual invoice numbers.

Either way, list the original ConnectWise invoice numbers somewhere on the document. Even on a merged invoice, tagging each line with its source invoice number saves a lot of back and forth when a client pays part of it or asks about one charge.

Choosing Which Invoices to Combine

The harder question is which invoices belong together. There are three approaches we use, and the right one depends on how your billing team works.

1. Every Current Invoice for the Company

The simplest rule: when you open or send one invoice, the template pulls every other current invoice for that company and combines them. “Current” usually means a specific status, like New or a custom status you create for invoices waiting to be combined.

This is easy to explain to your team, and it’s the approach most Report Writer master invoice templates use. The downside is that it depends on invoice status, and status changes. More on that below.

2. A Custom Field

Add an invoice custom field, then give every invoice you want combined the same value. ConnectWise can do this in bulk: select the invoices in the Invoice List, then use Actions > Update Custom Field to set them all at once.

When any one of those invoices is printed or sent, the template finds every invoice for that company with the same value. Because the value doesn’t change when an invoice is emailed or closed, the grouping stays stable. You can also use the value to pick the style, for example merged by default and collated when the value contains a keyword.

This takes one extra step from your billing team, but it’s the most reliable option and it lets you combine exactly the invoices you want, not just everything that happens to be open.

3. Dates or Other Rules

Some clients want everything from a billing period combined, or everything for one site, or all invoices except project billing. As long as the rule can be worked out from ConnectWise data, the template can apply it automatically, with no status or custom field for your team to manage.

Problems to Plan For

These are issues we’ve hit building combined invoices for clients. If you build your own, plan for each one.

Emailing can close the invoice first. If ConnectWise is set to close invoices when they’re emailed, the invoice may already be closed by the time your template renders the attachment. If your combining rule depends on status, the template no longer sees the group and sends a single invoice instead. The symptom is a combined invoice that prints correctly but emails as one page. Either turn off auto-close on send, or combine by custom field instead of status.
The API only returns 25 records by default. If you pull a company’s invoices through the ConnectWise API, set a page size (the maximum is 1,000) or page through the results. Otherwise a client with 30 open invoices gets a combined invoice with 25 of them and a total that doesn’t match.
Report Writer subreports are tied to the invoice being printed. The first level of subreport on an invoice template is automatically filtered to that one invoice number, so it can’t reach the company’s other invoices. The workaround is a subreport at the company level, with a sub-subreport inside it for the invoices. That works, but the sub-subreport has no idea which invoice started the print, which makes Report Writer combined invoices much more limited in what they can do.

Regenerating Combined Invoices Later

A combined invoice is easy to create while all of its invoices are open. It’s harder to reproduce a month later, after some have been paid and closed, which is exactly when a client asks for a copy or opens it from a payment portal.

In Report Writer, a master invoice is designed around current invoices, so regenerating an old one usually means reopening invoices or rebuilding the group by hand. With NexNow Hosted Invoices, we save which invoices were combined, and how, in your invoice history, so a combined invoice can be regenerated later, including from a payment portal. We still recommend keeping the original PDF as the copy of record, since that’s the document the client actually received.

Wrapping Up

If you’re building combined invoices yourself, pick the combining rule first, then work through the list above before you roll it out. If you’d rather not, combined invoices are available on NexNow Hosted Invoices for ConnectWise PSA with any of the combining methods above, and we also build master invoice templates in Report Writer if you’d like to stay there.