Moving accounting systems without losing your numbers

Sample Motors LLC is a made-up independent used-car dealer. It grew fast and changed systems twice. Everything here is invented: the company, the lenders, the systems and every number.

The same pattern fits any business that runs on industry software: restaurants, medical offices, contractors and stores.

Here are the steps of a move, in order. We set the dates with your staff and the new vendor.

1. Week 1: Pick the switch date. It is usually a month end. List every account that needs a starting number.
2. Weeks 1–2: Export what each old system can give: trial balance, ledger detail, schedules and the inventory list.
3. Weeks 2–4: Rebuild the tax books in QuickBooks Online from bank, lender, card and payroll records where the old system cannot be fixed.
4. Week 4: Build the opening balance file in the new system’s format, with the support behind every line.
5. Weeks 4–8: Run the first month in the new system with your staff and the vendor’s setup team, and check it against the old system.
6. Week 8: First close in the new system, for Month 1, with the checklist your staff will keep using.

Most moves are simpler than a dealer’s. Moving from QuickBooks Desktop to QuickBooks Online is a common one. The same steps apply. Here is the checklist we use.

• Pick the switch date, usually the end of a month or a quarter.
• Bring over open customer invoices and unpaid bills one by one, so each can be collected or paid in the new system.
• Carry over payroll and contractor totals for the year to date, so year-end forms come out right after a mid-year switch.
• Carry over the sales tax you owe on the switch date.
• Start each bank account from its last reconciled balance, with the uncleared checks and deposits listed.
• Decide how much history to bring: usually balances only, or the current year in detail.
• Keep the old file readable after the switch, so past years can still be looked up.
• Run the first month in both the old and new systems and compare them, then close it in the new system.

For each account we put three numbers side by side: what the old system shows, what the rebuilt books show, and the outside record. The rebuilt books always match the outside record. The last column is how far off the old system was.

Liabilities show as negative numbers. The bank gap is $25,500 of checks that cleared the bank months ago but were never entered in the old system. The inventory gap is four vehicles whose sales were posted without removing their cost from inventory. The Lender A gap is a principal payment that was posted as interest.

Inventory goes into the new system one vehicle at a time, with its stock number, cost and lender. The total of this list is the inventory number on the opening balance file.

Lender A finances 30 vehicles ($685,500). Lender B finances 9 ($177,500). The dealer owns 9 outright ($217,500).

Each lender’s statement is checked against the books and the lot, unit by unit. On the switch date, the lender statement, the books and the lot show the same units and the same balance.

Before the clean-up, Lender B showed two vehicles the books had already sold. Both payoffs were sent and the statement now matches.

This is the file the new system loads on the switch date: one line per account, debits equal credits, and a support reference for every number.

Owner equity is what is left after every other account is proven. Here it is $400,100. Cash-owned vehicles are part of inventory, with no loan against them.

In our experience, many dealer systems, System C included, won’t let you reopen a closed month. So a fix is booked in the current month, and this list keeps track of which month it really belongs to. The tax return can then be adjusted.

Opening balance entry

One entry in the new system on the switch date. It is the opening balance file above, in summary. Equipment is shown net of its $21,000 of depreciation, so the total is $1,368,400 instead of $1,389,400.

A fix found after the switch, booked in a later month

A vehicle sold in Month 1 was posted without its cost, so it was still listed in inventory. Month 1 is closed, so the fix goes in Month 3, with a note that it belongs to Month 1 and a line on the clean-up list.

Year-end depreciation, booked before the year locks

Depreciation choices are made before the system closes the year, so the books and the tax return use the same numbers.

These are the questions we raise with you and your tax preparer during a move. Each one is checked against the current IRS rules for your year.

• Which books is the return built from? When the industry software is wrong, the return should come from books that tie to the bank and the lenders. We keep a written list that ties each number in the system to the tax return.
• Inventory method. Vehicles can be tracked one by one at cost (specific identification). Changing how you count or value inventory is a change in accounting method, which usually takes Form 3115 (IRS Publication 538).
• The small business inventory rule. A business whose average yearly gross receipts are under the section 448(c) limit ($31 million for 2025, $32 million for 2026) can use simpler inventory rules under section 471(c). We check whether you qualify for the year.
• Depreciation at year end. Bonus depreciation and the section 179 deduction, two ways to write off equipment faster, changed in 2025. For example, property acquired after January 19, 2025 can qualify for 100% bonus depreciation, which writes off the full cost in the first year. We check the rule for each asset before the year closes.
• Fixing a prior return. If an old return used the wrong inventory or income, we ask whether to amend it. For an S corporation, that means an amended Form 1120-S. A partnership under the IRS partnership audit rules usually fixes a past return by filing an administrative adjustment request, a formal request to correct it, instead of sending amended K-1s.
• Entity type. We check that the IRS has the same tax classification you file under. The IRS letter that accepted your election (for an S corporation, the CP261 notice) settles it.
• Keeping the old records. The old system’s reports still count as business records. The IRS expects electronic records to stay readable for as long as they may matter for your taxes, so we export them in a form you can open after the old system is gone.