Payroll
Payroll that posts itself to the books
Every check is figured to the cent on Mastro's own tax engine, previewed, approved, and posted to the client's ledger. No second system to reconcile.
A pay run
From hours to a posted check
People and pay
Hourly and salaried people, bonuses, deductions and benefits, and each person's withholding forms. Social Security numbers and bank account numbers are encrypted and show as their last four digits.
A tax engine with no AI in it
Federal income tax, Social Security, Medicare, and the rules of all fifty states, every rate and table kept as data with the day it starts and the publication it comes from. The same pay always gives the same check.
Preview, approve, post
See every check before anything happens. Approving a run posts it to the client's books, and an approved run never changes: a mistake is corrected by another entry.
Stubs, files, and checks
Pay stubs in each person's portal, a direct deposit file for the client's own bank, and checks printed on the client's own check stock.
The filings
Prepared from the books, tracked until they're filed
Mastro prepares each payroll filing from the pay it figured. Your firm files it through its own channel and logs it in Mastro, which tracks every deadline.
- The deposit calendarWhat the client owes the IRS and each state, and the day it's due.
- Federal returnsThe 941 or 944 and the 940, figured from the year's checks.
- W-2s and the SSA's fileEach person's W-2, corrections, and the file the Social Security Administration takes.
- State wage reports and new hiresEach state's wage report and file, and new-hire reports.
- ACA formsForms 1094-C and 1095-C from the year's hours and coverage.
- A tie-out to the booksThe year's payroll figures checked against the ledger's accounts.
The money
Moved by the client's own bank, recorded by Mastro
Mastro isn't a bank. The client's own bank sends the direct deposits, and the client or its firm pays the tax deposits from its own accounts. Mastro figures every amount, makes the file the bank takes, and records each payment in the books.
Coming over
From Gusto, ADP, Paychex, or QuickBooks Payroll
The people and this year's payroll so far come over, so the next run continues the year's totals. A client that keeps its own provider can stay: Mastro posts its payroll from the provider's journal, or from its own connected Gusto account, previewed before anything posts.
Questions
Payroll, asked
Which states does it run payroll in?
All fifty, for 2026, on each state's own published rules.
What does it cost?
$19 a client a month, plus $4 for each person paid in the month, or $190 a year ahead plus $4 a person. Two or more modules on a client cost less.
Who moves the money?
The client's own bank. Mastro figures the pay and the taxes, makes the direct deposit file, and records each payment.
Who files the payroll returns?
Your firm, through its own channel. Mastro prepares each return from the books and logs the filing and its due dates.
Does AI figure the pay?
No. The tax engine is deterministic, and no model runs on the books. Your own Claude can start a pay run as you if your firm lets it, but never sees anyone's pay rate.