How Breevo checks its math

Checked against the IRS's own test returns

November 2026

In short: the IRS publishes sample Form 1040 returns for tax years 2025 and 2026. Breevo ran every one that fits what Breevo prepares – 11 returns in all. Breevo's numbers match on every line compared, except in four places where the IRS sample itself departs from that year's rules; there Breevo follows the rules (the four places are listed below).

What the IRS publishes

Each year the IRS posts test scenarios for software makers (its "Assurance Testing System", IRS Publication 1436): made-up taxpayers with their W-2s, 1099s and other forms. Of its 17 Form 1040 scenarios for tax years 2025 and 2026, 11 fall within what Breevo prepares. The others include farm income, household employees, energy and business credits, which Breevo leaves to a tax professional.

What Breevo found

4 scenarios come with the IRS's own filled-in return. Breevo matches the IRS line for line – income, deductions, tax, credits, payments and the refund – apart from three lines (items 1 to 3 below).
7 scenarios give only the inputs. Each return was worked out by hand from the IRS instructions and tax tables, and Breevo matches every line.
Working through them made Breevo better. The comparison turned up nine small differences (for example, rounding self-employment tax line by line, as the IRS does). Each was fixed as a general rule, so every return benefits.

The returns

Tax year	Scenario	What's in it	Result
2026	14	W-2, earned income credit, child tax credit	Matches every line (refund $9,348)
2025	12	W-2, self-employment income	Matches 8 lines; the business income deduction follows the rules (1 below)
2025	13	Married couple, W-2s, other credits	Matches 5 lines; uses the 2025 standard deduction (2 below)
2026	12	W-2, self-employment	Matches 8 lines; takes the business income deduction (3 below)
2025	2	Married couple, itemized deductions, a small business	Matches the hand-worked return
2026	2	Married couple, itemized deductions, a small business	Matches the hand-worked return
2025	5	Child care, education and earned income credits	Matches the hand-worked return
2026	4	Child care, education and earned income credits	Matches the hand-worked return
2026	5	W-2, refund split across accounts	Matches the hand-worked return
2026	6	W-2, gambling winnings, rental income	Matches the hand-worked return (4 below)
2025	8	Retirement income, dividends, Social Security	Matches the hand-worked return

Where Breevo follows the rules rather than the sample

These samples are built mainly to test the e-file format, and in four places they don't apply that year's rules. Breevo follows the rules:

2025 scenario 12: the qualified business income deduction is worked out on the business profit after the deductible part of self-employment tax and self-employed health insurance, as the Form 8995 instructions say.
2025 scenario 13: the married-filing-jointly standard deduction is $31,500, the amount on the 1040 itself after the 2025 law change (the sample uses the earlier $30,000).
2026 scenario 12: the business made a profit, so Breevo takes the business income deduction the rules give; the sample leaves it out.
2026 scenario 6: Breevo also takes the overtime deduction and business income deduction the rules allow, which the sample doesn't list.

What this means – and what it doesn't

These checks show that Breevo's math follows the IRS's own examples. They are not an IRS approval or certification of Breevo – the IRS doesn't certify tax apps this way. Breevo is a do-it-yourself tax preparation and planning app: it shows the rule behind every number, and you review, sign and file your return. These returns are part of Breevo's automated tests, which run on every change, so the checks keep holding as Breevo changes.

Source: IRS Publication 1436, Assurance Testing System (ATS) Guidelines for Modernized e-File Individual Tax Returns, and the IRS's tax year 2025 and 2026 Form 1040 ATS scenario pages. Every taxpayer in them is made up by the IRS.