Changing ERP? Don’t leave spend management until after go-live

The safest time to change your spend management tool is during an ERP migration, not after it. You redesign the chart of accounts once, your new ERP gets clean expense data from day one, and you avoid reopening integrations a few months after go-live.

An ERP migration is one of the biggest projects a finance team takes on. It means months of data cleansing, testing, training and, often, a parallel run with two systems. So when someone suggests changing your expense tool at the same time, the instinct is to say "not now".

It's an understandable reaction. But waiting usually turns one project into two. You migrate the ERP with your current expense processes, then reopen the chart of accounts, cost centres and integrations a few months later to bring in a new tool.

This guide explains why your ERP migration is the right moment to implement spend management software, how it works alongside your current and future ERP, and what the cutover looks like in practice.

Where ERP migrations quietly go wrong: the systems around the ERP

Most ERP project plans focus on the ERP itself: data migration, configuration, testing and training. The systems that feed it get less attention. Expense tools, corporate cards, supplier invoices, payroll and banking all send data into the ledger, and each one has to be remapped when the chart of accounts changes.

Spend is the busiest of these flows. Card payments, receipts and invoices arrive every day, from people across the business, not just finance. If that flow isn’t ready for the new ERP, the problems show up in the first month-end close: miscoded expenses, missing VAT, and suspense accounts that someone has to clear by hand.

In our conversations with finance leaders, the same three concerns come up again and again:

• Capacity. The team is already stretched by the ERP project and can't take on another implementation.
• Building twice. If expense categories are set up for the old ERP, won't they have to be rebuilt for the new one?
• Integration risk. Will the expense tool still connect once the new ERP goes live?
  Each concern is reasonable. But each one is also a reason to do spend management as part of the ERP migration, not after it.

Five risks you remove by bringing spend management into the ERP project

1. Designing the chart of accounts twice
An ERP migration is when finance revisits accounts, sub-accounts, cost centres and analytical dimensions. If you define expense categories in the same exercise, they line up with the new structure from the start. Do it later, and you'll be mapping a new tool onto an ERP that has only just stabilised.

2. A second, unplanned migration after go-live
Anything you implement after go-live means remapping categories, reviewing export formats and retesting integrations. That's a second, smaller migration your team has to plan, staff and sign off.

3. Renewing a tool that won’t connect to your new ERP
ERP projects slip; contract renewal dates don't. Renewing your current tool by default can tie you to a system that has no integration with your new ERP, and you'll find out just as the new system goes live.

4. Finance capacity drained by manual work during the project
Card payments, receipts and supplier invoices keep arriving every day of the ERP migration. If that flow is already automated, your team spends its hours on the migration, not on chasing receipts and keying in invoices.

5. A messy first close in the new ERP
Expenses arrive in the new ERP already coded with the final structure, with VAT split out and the receipt attached. No clean-up project in month two.

How spend management works alongside two ERPs

Here’s how that works in practice with Payhawk. The key idea is simple: a spend management platform sits on top of your ERP, not inside it. Cards, expenses, supplier invoices and reimbursements are managed in Payhawk. During the migration, the only thing that changes is where the data is exported.

• Before cutover: your current ERP. Payhawk exports to the system you use today, either through a native integration or through configurable export templates for systems such as A3, Sage 200 or Navision.
• At cutover: switch the integration. You set a cutover date. Ideally, it's right after you close the month in the old ERP. Expenses before it stay with the old ERP; new ones go to the new ERP. The "Exported into" filter shows which system each expense went to, so each period stays separate.
• After cutover: your new ERP. A native integration syncs master data such as the chart of accounts, tax codes, cost centres and suppliers, so expenses are always coded against current data.

Map your chart of accounts once, not twice

In Payhawk, each expense category is linked to a general ledger account in your ERP, along with its tax code and dimensions such as cost centre, department or project. When you change ERP, you change that link. Employees keep seeing the same categories in the app, so nothing changes for them.

For example, if you move from A3 to Business Central, your employees keep the same three Payhawk categories, and each one simply points to a new account:

• Travel: from 62900000 Other services in A3 to 6290010 Travel, Sales cost centre in Business Central
• Insurance: from 62500000 Insurance premiums in A3 to 6250000 Insurance premiums in Business Central
• Marketing and events: from 62700000 Advertising in A3 to 6270020 Events, Marketing cost centre in Business Central

That's why it pays to design your categories alongside the new ERP. If the chart of accounts stays the same, the switch is simple. If it changes, you update the mapping per category, not expense by expense.

ERP migration: what changes in Payhawk and what stays

Changing ERP doesn’t mean rebuilding your spend setup. Your workflows, approval setups and configurations in Payhawk carry over as they are. What changes is where your expenses go and the data that comes from the ERP.

After cutover, expenses are exported to the new ERP, which automatically syncs its own fields and values into Payhawk. Values from your previous ERP are archived and replaced by their new equivalents, so cost centre fields from DATEV, for example, are replaced by the ones in NetSuite.

Three things to plan for:

1. Close the month before you migrate. Switching mid-period means postings for the same month end up in two systems.
2. One Payhawk entity connects to one ERP at a time. If your entities move at different times, each entity can connect to its own ERP.
3. Test sandbox to sandbox. Standard practice is to connect a Payhawk sandbox to your new ERP's sandbox and test the full flow before cutover.

What spend management takes off your team's plate during the migration

An ERP migration absorbs your finance team for months. Meanwhile, expenses don't wait. Here's how the most time-consuming manual tasks change:

• Keying in receipts and invoices line by line. OCR extracts the data, and the expense arrives pre-coded with category, tax and cost centre.
• Assigning the right GL account to every expense, twice during a parallel run. Accounts are assigned by category, so you change the mapping, not each expense.
• Chasing card receipts by email at month-end. Employees snap the receipt in the app when they pay and get automatic reminders.
• Reconciling card statements against receipts. Each Payhawk card transaction appears in real time, and the receipt attaches to it as soon as the employee captures it.
• Managing approvals by email and spreadsheet. Approval workflows run by amount, team, category or cost centre, with a full audit trail.
• Rebuilding export files every time the ERP format changes in testing. Your team configures export templates itself, with no development needed.

The result: your team spends its time on what only it can do during the ERP migration, such as validating balances, reviewing the account structure, testing processes and training users.

ERP migration checklist for your spend management setup

• Start on your current ERP. Use the native integration or an export template so card spend and expenses are automated straight away.
• Design for the new chart of accounts. Set up categories, cost centres, custom fields and approval workflows to match the new ERP's configuration.
• Test in a sandbox. Connect a Payhawk sandbox to your new ERP's sandbox and run real expense scenarios through it before cutover.
• Set the cutover date. Close the month in the old ERP first, then connect the new ERP in production and use the export filter to keep each period separate.
• Let master data sync. Suppliers, tax codes and dimensions sync from the new ERP, so coding stays accurate as the ERP evolves.
• Review after the first close. Check mappings and workflows against the first month-end in the new system.

The Implementation Agent can guide your team through the setup alongside your implementation manager.

What implementing spend management during an ERP migration looks like in practice

Payhawk customers have made the switch across very different ERP moves:

• A multinational technology financing group rolled out Payhawk on its legacy ERP, with export templates designed for its later move to SAP S/4HANA Cloud. When the new ERP arrived, there was no need to reimplement the expense programme.
• A software company kept the same spend setup through two ERP changes, from QuickBooks to Business Central and then to NetSuite. Before go-live, the team mapped expense categories and GL accounts to the new system and tested the integration in a sandbox.
• A Spanish production company connected Payhawk to NetSuite through a sandbox first, migrated historical expenses and mapped departments and projects to NetSuite's tracking categories.
• A Spanish retail chain implemented Payhawk while moving from A3 to Business Central Cloud. Cards, supplier invoices, purchase orders and per diems now post to Business Central with cost centre and VAT.
• A fast-growing SaaS company chose Payhawk during its move from DATEV to NetSuite and kept it through the switch, including its US entity, without re-tendering its expense tool.

FAQs about spend management and ERP migration

Do I have to wait until my ERP migration is finished?
No. You can start with your current ERP and switch the integration when the new system goes live.

What if my current ERP doesn't have a native integration?
You can use an export template in the format your ERP imports. That's common with systems such as A3 or Sage 200.

Do I need to reconfigure everything when I change ERP?
No. Workflows, approval setups and configurations carry over. What changes is the export destination and the master data: the new ERP syncs its own fields and values, and old values, such as cost centres from your previous ERP, are archived and replaced by their new equivalents.

Can I test the new ERP integration before go-live?
Yes. The standard approach is to connect a Payhawk sandbox to your new ERP's sandbox and test the full flow before cutover.

Can Payhawk connect to my old and new ERP at the same time?
Not from the same entity: each Payhawk entity connects to one ERP at a time. If different entities move at different times, each can connect to its own ERP in parallel.

Which ERPs does Payhawk integrate with?

Payhawk has native integrations with Microsoft Dynamics 365 Business Central and Finance, Oracle NetSuite, SAP S/4HANA Cloud, Sage Intacct, DATEV, Xero, Exact Online and QuickBooks. For other systems, configurable export templates and the Payhawk API cover the rest. See all integrations.

Further reading in the Payhawk Help Center

• Supported ERP systems
• Automating master data sync between Payhawk and your ERP system
• Overview of exporting and downloading expenses and payments
• Managing the accounting templates
• Client testing: checklist for integrations and accounting export
• FAQ on ERP systems

De-risk the migration, not just the ERP

An ERP migration succeeds or fails at the first close, and the first close depends on everything that feeds the ledger. Bringing spend management into the project means you design your finance structure once, your new ERP gets clean data from day one, and your team isn’t keying in receipts while it validates balances.

Planning an ERP migration? Book a demo and we'll show you how Payhawk fits your migration timeline, with your current ERP and your new one.