By default, Productive calculates invoice totals per line item, meaning tax is applied and rounded on each line separately before summing for the total.
This is the most precise method per item, but you may occasionally notice a difference of one or two cents between the total and the sum of all line items — for example, on a budget, report, or invoice.
This isn’t a bug. It’s an expected rounding difference that comes from how and where numbers are calculated.
Why does this happen?
Productive stores all values from time entries, budgets, and services with full precision (several decimal places). For clarity, most screens and invoices show values rounded to two decimals.
When values are grouped or rounded at different stages, small differences in totals can appear — for example, between a budget and an invoice.
📌 These rare cases usually happen when line items include discounts or markups with three or more decimal places, such as a 4.319% discount.
Example
Let’s look at a real-world case from a budget screen where there’s a 1 cent difference between:
The Budget Remaining value in the Overview tab
The Budget Remaining value in the Services tab
The cause of this small difference is the Junior service, which is priced at €200.19 per hour and has a 4.319% discount applied to 93 hours.
Productive calculates the values using full precision, then rounds the totals for display. This is what can lead to a small visual mismatch.
Detailed explanation below (click to expand 👇)
Detailed explanation below (click to expand 👇)
Here’s how it works behind the scenes for the Junior service line item:
The full discounted rate is calculated as:
(200.19 - 200.19 × 0.04319) × 93 = 1781357.283270 (stored in cents)
👉 On the screen, we show this as €17,813.57 for the Budget TotalSomeone tracks 4.35h on the Junior service:
(200.19 - 200.19 × 0.04319) × 4.35 = 83321.550346 (stored in cents)
👉 On the screen, we show this as €833.22 for the Budget Used
So when we look at the interface:
Budget total (displayed): $17,813.57
Used (displayed): $833.22
Remaining (displayed calculation): 17,813.57 - 833.22 = €16,980.35
👉 But the remaining value shown on the screen is €16,980.36
Why the mismatch?
Because the actual calculation uses full precision:
1781357.283270 - 83321.550346 = 1698035.732924 (in cents)
👉 Rounded for display: €16,980.36
Where This Happens
This kind of difference can appear:
Between the total shown in the budget overview and the sum of individual service lines
Between invoices, reports, and budget screens
When using precise discount/markup rates with 3 or more decimals
In all these cases, Productive uses full precision for calculations but rounds for display.
What about taxes?
Some users might notice a discrepancy in the total tax amount on invoices. This happens because, by default, Productive applies tax at the line-item level, rounds each tax amount to two decimals, and then sums them up.
📌 This means each line is taxed individually before adding up, rather than applying tax once to the full total.
That total might not match the tax you’d get if you:
Calculate the subtotal first
Then apply the tax rate to that subtotal
This isn't a bug, it's just one of two common accounting conventions:
Systems like Xero and Exact calculate tax per line item (as Productive does)
Systems like QuickBooks calculate tax on the subtotal
There’s no single “correct” way: it depends on the accounting approach. Since we can’t support both methods in parallel, it's important to know that Productive calculates tax per line item.
Where to adjust rounding
If you need more flexibility in how invoice totals are calculated, or want them to match your accounting software, you can go to Settings > Invoicing > Rounding Methods (Admins only) and choose either Per line item or Per subtotal.
👉 Learn more in the Invoice Rounding Methods article.
What about "Left for Invoicing" amounts?
You might see small amounts like $0.01 left for invoicing. This is also caused by rounding and is a known behavior. If this happens, you can manually mark the budget as fully invoiced if needed.
👉 Learn how to manually mark the budged as invoiced in Marking a Budget as Invoiced.
What does this mean for you?
These rounding differences are standard and don’t affect the accuracy of your data
They typically appear only in edge cases involving high-precision discounts or markups (like the 4.319% discount on the Junior service).
Your reports and totals still reflect correct values based on precise calculations.
Still unsure? Reach out anytime, we’re happy to review your numbers with you ☎️