Full service payroll is the tier where a payroll provider calculates gross-to-net wages for each pay cycle, withholds the right federal and state taxes from each employee, deposits those taxes with the IRS and the state on the right cadence, files Form 941 quarterly and Form 940 annually on your behalf, generates and files W-2s at year end, handles new-hire reporting,
and provides a dedicated payroll specialist you can call when a W-2 needs reprinting or a deposit missed by a day. Self-service payroll is the same math, only without the filings and deposit step;
PEO is co-employment, where the PEO pays under its own EIN. Full service is the middle tier between self-service and PEO, and it’s the tier that most small businesses hire.
Run a quick stress-test: the day you have 3 to 30 W-2 employees and one person who runs payroll as a side responsibility (you, your office manager, your bookkeeper who also handles 4 other clients), the operational value of full service is highest.
The savings of self-service ($5-$15 per employee per month) is real but the cost of a missed Form 941 is $1,250 to $12,500 per occurrence, and the cost of a missed federal tax deposit can be 2% of the underdeposit per month late.
Three missed deposits in a year wipe out a decade of self-service savings for almost any small business.
Full service payroll is the right tier when you have 1 to 50 W-2 employees and no dedicated payroll person on staff. It is not necessary when you have zero W-2 employees, and it is not sufficient when you have over 50 employees across multiple states with payroll-tax complications that require a PEO.
Key facts: Full service payroll is the standard plan tier at Gusto, OnPay, QuickBooks Payroll Premium, Patriot Full Service, ADP RUN, and Paychex Flex.
Base monthly fee runs $39 to $99 depending on vendor and tier; per-employee fee runs $6 to $12.
The canonical entry-tier full-service plan is Gusto Simple at $40/month base plus $6/employee per month.
Full service includes: gross-to-net calculation, federal tax deposits, state tax deposits, Form 941, Form 940, W-2 generation and filing, new-hire reporting, employee self-service portal, and direct deposit.
It typically excludes: state unemployment insurance setup ($50-$100/state one-time), W-2 reprint after the second copy ($5-$20/W-2), and HR consulting beyond a baseline knowledge base.
At 5 W-2 employees on a full-service plan, the realistic monthly bill is between $80 and $180 per month: base fee plus per-employee fee plus typical add-on cost for state registrations and W-2 paper handling.
Below 3 employees, a self-service plan saves $20-$40/month and is reasonable for an owner who already does QuickBooks.
Above 30 employees, full-service plan tier becomes expensive per-head and a PEO quote becomes worth it.
What “full service payroll” actually includes, line by line
The phrase gets stretched in marketing copy. Here is the standard scope based on the canonical definitions from Gusto, ADP RUN, Paychex, and IRS guidance.
| Step | What the provider does | What you do |
|---|---|---|
| Employee onboarding | Collects W-4, I-9, state new-hire form | Provide employee info, sign forms |
| New-hire state reporting | Submits to state within 14-20 days | Nothing |
| Pay run calculation | Gross-to-net, federal tax, FICA, state tax | Enter hours or confirm salary |
| Direct deposit | Sends net pay to employee bank accounts | Approve the pay run |
| Federal tax deposit | Submits via EFTPS, semi-weekly or monthly | Nothing |
| State withholding deposit | Remits to state tax agency on state’s cadence | Nothing |
| State unemployment | Remits SUTA + files quarterly | Nothing beyond initial state registration |
| Form 941 (quarterly) | Files by month-end after each quarter | Nothing |
| Form 940 (annual) | Files by January 31 | Nothing |
| W-2 and 1099-NEC | Generates, files with SSA + IRS, mails to employees/contractors | Verify totals |
| Year-end reconciliation | Reconciles Forms 941/940/W-3 against deposits | Approve |
| Dedicated support | Phone, chat, email with response SLA | Contact when needed |
For the entity definition and how each step works in detail, the what is a payroll service page walks through the gross-to-net, deposits, and filings step by step. For the cost math at each plan tier and the per-employee fee math the vendor sites hide, the payroll service cost page runs the per-state and per-add-on math.
What full service does NOT include (the boundary your marketer will skip)
Three classes of work are commonly excluded from the headline full-service tier. Knowing each keeps you from assuming coverage that doesn’t exist.
State income tax and SUTA setup. The first time your business hires an employee in California, the provider must register with the California EDD (Employment Development Department) for state withholding and the California Employment Training Tax.
The first-time registration takes 10-30 days and almost no provider does it for free.
Gusto charges $39/state for SUI setup; ADP RUN charges by state; Paychex bundles it into onboarding.
W-2 reprint and amendment. Each provider includes one W-2 per employee at year end. Subsequent reprints (when an employee loses theirs, requests a duplicate, or has a name correction) run $5-$20 per reprint. W-2c filings (corrected W-2 after the SSA deadline) run $50-$100 per correction. These fees are not in the marketing copy.
HR consulting and employee-relations support. Full-service tier includes a baseline payroll-specialist support line and a self-serve HR knowledge base.
It does not include an HR consultant for hire-vs-fire situations, employee handbook drafting, or HR-compliance audits.
For most small businesses, the payroll specialist answers “how do I classify this contractor as W-2 vs 1099” and similar tactical questions; for anything more, upgrade to the premium tier or buy HR-as-add-on.
Full service vs self-service vs PEO: when each is the right tier
The full-service tier is one of three canonical choices. The decision turns on employee count, state complexity, and whether you want to keep the EIN-related filings under your own control.
Self-service payroll. The math is automatic; you make the tax deposits and submit the forms.
Patriot Software Basic at $17/month base + $4/employee is the canonical self-service tier.
The savings are meaningful for a very small team; the operational burden is real for an owner who already has a full-time job that isn’t payroll.
Generally useful at 1-3 employees for a small business that already runs QuickBooks.
Full-service payroll. The math and the filings are automatic.
Gusto Simple at $40/month base + $6/employee, OnPay at $49/month flat + $6/employee, QuickBooks Payroll Premium at $88/month base + $12/employee, ADP RUN at $79/month base + $15/employee, and Paychex Flex at roughly $65-$100/month base + $15-$25/employee are the canonical full-service tiers.
The right choice for 1 to 50 W-2 employees when you don’t have a dedicated payroll person.
PEO (Professional Employer Organization). The PEO becomes the co-employer; it pays your W-2 employees under its own EIN, files all the taxes, and provides benefits and HR as a single contract.
Justworks at $56-$149/employee/month is the canonical PEO for small business.
The benefit: scale on benefits (group health, 401k plans that you couldn’t access as a 5-person LLC) and a single liability chain.
The trade-off: the PEO owns your EIN-related filings, and changing PEOs is a one-time project.
| Tier | Best employee count | Best state complexity | Why |
|---|---|---|---|
| Self-service | 1 — 5 | Single state | Lowest cost; you do the filings |
| Full service | 1 — 50 | Up to 5 states | Math and filings both automatic |
| PEO | 10 — 200 | Multi-state or multi-entity | Co-employment, benefits access |
Where full service falls short
Full service is the right tier for most small businesses. It is not a perfect tier for three scenarios where the next step up is warranted.
Multi-state with high turnover. If you operate in five states and hire/fire at high cadence, full-service providers charge a state setup fee and per-state ongoing fees that add up to $50-$200/month in pure compliance overhead. A PEO bundles that overhead into its per-employee fee and is more cost-effective above 15 employees across 3+ states.
Multi-entity ownership. If you have an LLC plus an S-corp plus a C-corp all on the same payroll account, the full-service provider handles each as a separate payer with a separate EIN report, which is correct and clean. The PEO model is harder to apply cleanly because the PEO becomes co-employer of one entity, not multiple.
International footprint. Full-service US payroll does not include international employer-of-record, contractor of record, or country-specific filings. For international hires, the canonical solution is a global payroll partner like Deel, Remote, or Rippling’s international module (at $8-$40/employee/month for international, plus country-specific costs).
The honest traps in full-service marketing
Three phrases in vendor marketing are worth parsing before you sign.
“Unlimited payroll runs” is a real inclusion. Some providers gate the number of monthly pay runs (e.g. “monthly payroll included; bi-weekly is $20/rerun extra”). On most modern full-service tiers, unlimited pay runs is standard. Verify before signing — for a team that pays weekly or bi-weekly, a per-run fee doubles the effective monthly cost.
“Tax filing included” refers to federal, not always multi-state. Federal tax filing (Form 941, Form 940) is universally included. State tax filing is included for the state where the provider sees your first employee; each additional state of operation is usually a per-state setup fee plus a per-state filing fee in the ongoing cost.
“W-2 included” refers to one printed W-2 per employee. Reprints run $5-$20 per W-2. If your employee names, SSNs, or addresses change after January 31, the corrections cost more. Most providers include the W-2c filing for the first 30 days after the original W-2 was issued at no extra charge; after that, fees apply.
Pick full-service when the math at your employee count justifies it
The rule of thumb: full-service is justified when your time + the cost of one missed filing exceeds the price difference between self-service and full-service. For almost every business with 3+ W-2 employees, that is true on day one.
For the per-employee cost math at each plan tier (Gusto Simple, OnPay, QuickBooks Payroll, Patriot Full Service, ADP RUN, Paychex Flex, plus the modular alternative Rippling), the payroll service cost page runs the per-state and per-add-on math at each employee count.
For the broader definition of what a payroll service does in plain English, the what is a payroll service page walks the gross-to-net, deposits, and filings step by step.
For the comparison across the six credible providers at full-service level, the best payroll service for small business comparison goes through the math at each employee count and a Lookout for which provider fits which team shape.
For the federal and state paperwork that accompanies each pay cycle, the payroll tax filing page walks Form 941, Form 940, W-2/W-3, and the state filings cadence.
Last updated: October 2026
