A reference for the parts of federal filing that nobody explains the first time.

Why April 15 isn't always April 15

The statutory deadline for filing the federal individual return is April 15. When that date falls on a Saturday, Sunday, or a District of Columbia holiday — most often Emancipation Day on April 16 — the deadline rolls to the next business day for everyone in the country. Returning filers who lived through the 2020 and 2021 seasons saw exactly that.

Maine, Massachusetts and Patriots' Day

Filers whose returns are processed through the Andover or Massachusetts service points get an additional one-day shift when Patriots' Day (the third Monday of April) lands on or after April 15. The shift is automatic; no form is required.

Federally declared disaster areas

When a county is included in a FEMA disaster declaration, residents and businesses in that county routinely receive a postponement — often to October or later. The list of qualifying counties is published as a news release and updated through the season; check before assuming you owe a late penalty.

If you simply need more time

Filing Form 4868 on or before April 15 buys an automatic six-month extension to file — through October 15. The extension grants extra time to file, not to pay: any balance due is still calculated as of April 15 and accrues interest from that date.

Free File — guided software, AGI ≤ $89,000

The free guided-software program is a public-private partnership: a panel of trusted commercial preparers offer their products at no cost to filers under an income cap. For the 2026 filing season the federal cap is adjusted gross income of $89,000 or less — a $5,000 increase over the 2025 season and one of the largest annual lifts in the program's history. Eight partners participate; two of them (OLT and FreeTaxUSA) include free state filing for any state that meets the federal eligibility.

Free Fillable Forms — no income limit

For filers above the AGI cap who are comfortable with the actual forms, Free Fillable Forms remain available with no income limit. The interface is essentially a digital version of the paper return: it does math but does not give guidance. Best suited to filers who already know which schedules they need.

VITA and TCE — in-person help

The Volunteer Income Tax Assistance and Tax Counseling for the Elderly programmes provide in-person preparation by certified volunteers, generally for filers with income under approximately $67,000, persons with disabilities, the elderly, and limited-English-proficiency filers. Sites are listed by ZIP code through the federal locator tool and through AARP for the elderly programme.

File anyway — the penalties are not the same

Two distinct penalties exist, and confusing them costs filers thousands of dollars a year. Failure-to-file accrues at 5% of unpaid tax per month, capped at 25%. Failure-to-pay accrues at 0.5% per month, also capped at 25%. The first is ten times the second. If you cannot pay, the priority is to file on time and address the balance later.

Short-term payment plan — up to 180 days

Filers who can clear the balance within 180 days can request a short-term plan online. There is no setup fee, and interest continues to accrue on the unpaid balance, but the failure-to-pay penalty is reduced once the plan is in place. Most balances under approximately $100,000 qualify automatically.

Long-term installment agreement — Form 9465

For balances above what a short-term plan can absorb, an installment agreement spreads payment over up to 72 months. Setup fees apply (lower for direct-debit), and the application itself is normally Form 9465. Filers with assessed balances under $50,000 can usually be approved through the online application without paperwork.

Offers in compromise — narrow but real

An offer in compromise settles a balance for less than the assessed amount, but only when the agency concludes that full collection is unlikely. The qualifying threshold is high; do not pay a third party who promises an offer before assessing your specifics, and start by running the official pre-qualifier published with the offer-in-compromise booklet.

Step 1 — Identifying information and filing status

Name, address, Social Security number, and the box for filing status: single or married filing separately, married filing jointly or qualifying surviving spouse, or head of household. The status here is the status you will use on the return — not a withholding-only choice.

Step 2 — Multiple jobs / working spouse

This is the step most filers skip and then wonder why they owe in April. If you hold a second job, or your spouse works, the default withholding tables assume only one job and under-withhold across the household. Three options resolve it: (a) check the box in 2(c) if there are exactly two jobs and pay is roughly equal, (b) use the multiple-jobs worksheet, or (c) use the online estimator. The estimator is the most accurate; the box is the easiest.

Step 3 — Claim dependents

Multiply qualifying children under 17 by $2,000, other qualifying dependents by $500, and enter the total. This is how the Child Tax Credit reduces your withholding throughout the year rather than waiting until you file. There is an income phase-out at higher incomes; if your household is above the phase-out threshold, leave Step 3 blank.

Step 4 — Other adjustments

Three optional lines: (a) other income such as interest or dividends, on which you want tax withheld through the paycheck rather than estimated quarterly, (b) deductions above the standard deduction, and (c) any additional flat dollar amount to withhold per pay period. Line (c) is the most useful — it is the simplest way to fix any chronic shortfall without re-doing the rest of the form.

Step 5 — Sign and date

An unsigned W-4 is treated as if the highest withholding category had been selected. If you simply want maximum withholding while you sort out a more accurate version, leaving everything blank and signing is a valid strategy.

Who actually owes estimated tax

The threshold is whether you expect to owe at least $1,000 after subtracting withholding and refundable credits. Self-employment income, investment income above what is withheld at source, rental income, and large one-off capital gains are the usual triggers.

The four installments

Each due date follows the same weekend-and-holiday rules as April 15. The vouchers are Form 1040-ES, but most filers pay electronically through Direct Pay or EFTPS and never touch the paper.

The safe-harbour rule — 90 / 100 / 110

Penalties for under-withholding are waived for the year when total payments equal or exceed any one of the following: 90% of the current year's tax, 100% of the prior year's tax (110% if last year's AGI exceeded $150,000), or any amount that leaves a balance due of less than $1,000. The 100/110 figure is the easiest to plan around: divide last year's total tax by four and pay that amount on each due date, regardless of how the current year shapes up.

Return Received

The return has been accepted into the processing pipeline. Accepted is not the same as approved — at this stage the return has only passed an initial validity screen (matching SSN, supported forms, valid signatures). Most returns sit in this state for one to seven days while line-item math and matching against employer-reported income are completed.

Refund Approved

Processing is complete and a refund amount has been calculated. A specific deposit or check date is shown when the funds are scheduled to leave the agency. The headline 21-day target — i.e., e-filed return with direct deposit, no errors — is measured to this point.

Refund Sent

The funds have been released. For direct deposit, the bank typically posts within 1–5 business days; for a paper check, allow up to four weeks for postal delivery. If a deposit is rejected by the bank (closed account, wrong digits), the system automatically converts to a paper check sent to the address of record.

If your refund includes EITC or ACTC

By federal law, refunds for returns claiming the Earned Income Tax Credit or the refundable portion of the Child Tax Credit cannot be released before mid-February, regardless of when the return was filed. This is the PATH Act hold; it applies to the entire refund, not only the credit portion. Filing earlier helps the queue position; it does not move the floor.

The paper-check tax

A paper refund check is mailed from a regional finance centre, posted via standard first-class mail, and may take three to four additional weeks beyond the deposit date — and far longer in the event of a postal disruption. Lost-check tracing typically requires waiting an additional 28 days from the issue date before a replacement can even be requested.

Splitting into up to three accounts

A single refund can be deposited into up to three separate accounts at one or more financial institutions using Form 8888. The three slices can be any combination of checking, savings, retirement (IRA), or even savings bonds. The form is filed with the return; software handles it as part of the deposit-information section.

Validating the routing and account numbers

Refund deposits use the routing and account numbers exactly as entered. There is no name-matching at the receiving bank — funds will land in whatever account the digits identify. Verify routing/account against a recent statement, not against a memory or against numbers printed on a void cheque from a closed-and-reopened account.

The legal standard, in one sentence

An expense is deductible on Schedule C when it is ordinary (common in your industry) and necessary (helpful for the business). The standard is generous; the documentation requirement is not. Keep contemporaneous records — receipts, calendar entries, mileage logs — rather than reconstructing them in March.

Categories that show up on every Schedule C

• Advertising (line 8): online ads, business cards, sponsored posts, listing fees.
• Car and truck (line 9): standard mileage or actual expenses, not both, and the choice in year one of using the vehicle is partially binding.
• Contract labor (line 11): payments to non-employees of $600+ trigger a 1099-NEC filing requirement.
• Office expense (line 18): consumables — paper, pens, postage. Not equipment.
• Supplies (line 22): items used up in the business and not held as inventory.
• Travel (line 24a) and meals (line 24b, 50% deductible).

Home office — simplified vs regular

The simplified method gives a flat $5 per square foot, capped at 300 square feet ($1,500 ceiling) — no depreciation, no allocation of utilities. The regular method tracks actual costs and a depreciation schedule on the business-use portion of the home. The simplified method is often the right answer for under-1,000-sq-ft apartments and home offices used part-time; the regular method wins for high-cost areas with dedicated rooms.

What does not belong on Schedule C

• Personal commuting from home to a fixed work location.
• Clothing usable as ordinary street wear, even when worn only at work.
• Penalties and fines paid to a government.
• The half of self-employment tax that is itself a deduction — that goes on Schedule 1, not Schedule C.

What the 15.3% actually is

Self-employment tax is the combined Social Security (12.4%) and Medicare (2.9%) contribution that an employer and an employee normally split on a W-2. A self-employed filer pays both halves, which is where the 15.3% headline figure comes from. It applies to 92.35% of net self-employment earnings — the small adjustment exists to roughly equalise the treatment with W-2 employees.

The Social Security wage cap

The 12.4% Social Security portion only applies up to the annual wage base, which is adjusted each year. Earnings above the cap are subject only to the 2.9% Medicare portion (plus the 0.9% Additional Medicare Tax on the slice of earned income above $200,000 single / $250,000 joint). For most self-employed filers this only matters once self-employment net earnings exceed roughly $170,000 in a year.

The deduction that softens the blow

One half of self-employment tax is deductible above the line — it reduces adjusted gross income directly, on Schedule 1. This is calculated automatically by software but is worth understanding when modelling whether to incorporate.

When forming an S corporation starts to make sense

Once net self-employment earnings stabilise above approximately $60,000–$80,000, the S-corporation election begins to plausibly save more in self-employment tax than it costs in payroll, additional bookkeeping, and a separate corporate return. Below that band the savings rarely cover the friction. The decision turns on the reasonable-compensation rule: an S-corp owner-employee must pay themselves a reasonable W-2 salary before taking the rest as a distribution, and that salary still bears the full 15.3%.

The numbers for tax year 2025 (returns filed in 2026)

For tax year 2026 (returns filed in 2027), these rise modestly to $16,100 / $24,150 / $32,200 respectively as part of the annual inflation adjustments.

When itemising still wins

Itemising on Schedule A is worth running the numbers on whenever any of the following apply: a mortgage on which deductible interest is meaningful (capped on principal up to $750,000 for loans originated after Dec 15, 2017), large charitable contributions documented with receipts, significant medical expenses exceeding 7.5% of AGI, or — much less commonly — a year with a federally declared casualty loss.

The SALT cap

The state-and-local tax deduction is capped at $10,000 in aggregate (state income tax + property tax + state sales tax). In high-tax coastal states this single cap is what tips most filers from itemising to the standard deduction even when their other Schedule A items are real.

Practical rule

Run Schedule A. If your itemised total is within $1,500 of the standard deduction, take the standard — the documentation cost and audit-exposure trade-off rarely justifies a marginal advantage. If itemised exceeds the standard by more than $2,000, itemise.

Who counts as a qualifying child

A qualifying child for the credit must be under 17 at year end, your son, daughter, stepchild, foster child, sibling, half-sibling, or a descendant of any of these (a grandchild, niece, nephew). The child must have lived with you for more than half the year, must not have provided more than half of their own support, and must have a valid Social Security number issued before the return's due date.

The credit and its refundable portion

The credit is up to $2,000 per qualifying child. Up to $1,700 of that (for tax year 2025) is the Additional Child Tax Credit — the refundable portion that can be paid out as part of the refund even when the credit exceeds the income tax otherwise owed. The refundable portion is calculated on Schedule 8812.

The phase-out

The credit begins to phase out at modified AGI of $200,000 single / $400,000 married joint, at a rate of $50 per $1,000 of AGI over the threshold. Most filers with kids never approach the phase-out; for those who do, modelling the impact of a Roth conversion or large bonus is worth doing before December.

Other dependents

Non-qualifying-child dependents — for example a parent you support, or a child aged 17 or older — qualify for the smaller $500 Credit for Other Dependents. It is non-refundable and uses the same income phase-out thresholds.

Maximum credit, tax year 2025

The income ceilings

For tax year 2025 returns, the credit phases out completely at adjusted gross income of approximately $19,104 (no children, single) up to $68,675 (three or more children, married filing jointly). The exact phase-out band depends on filing status and number of qualifying children; the agency publishes the full table each year.

The fixed eligibility floor

• You must have earned income — wages, salary, or net self-employment earnings. Investment income alone does not count and is itself capped (filers with investment income above approximately $11,950 for 2025 are disqualified outright).
• Filing status cannot be married filing separately, except in narrow separation circumstances.
• The filer, spouse, and any qualifying children must each have a valid SSN, not an ITIN.
• The filer and spouse must be U.S. citizens or resident aliens for the full year.

You have to file even if not required

The credit is refundable, and many filers eligible for it have income low enough that no return would otherwise be required. The credit is forfeited if the return is not filed; an estimated one in five eligible filers leaves it on the table each year, almost always by simply not filing.

The number is the type

Every notice carries a CP-prefixed number in the top-right of the first page. The number identifies the underlying issue, the response window, and whether a payment is being demanded or a clarification is being sought. Reading the body without the number is like reading a verdict without knowing the charge.

CP14 — Balance due, first notice

You have a balance from the most recently filed return. Response window: pay or respond within 21 days. If the amount is correct, pay it; if it is not — for example, a payment was credited to the wrong year — call the number in the upper-right of the notice with the prior payment confirmation in hand. CP14 escalates to CP501 → CP503 → CP504 if ignored, with each step adding penalties.

CP2000 — Income mismatch, proposed adjustment

Information returns received by the agency (W-2s, 1099s, K-1s) do not match what was reported on your return. Response window: 30 days. A CP2000 is a proposal, not an assessment — read the line-by-line comparison carefully. If the proposed adjustment is correct, sign and pay; if it is partially correct (e.g., the unreported 1099-NEC is real but you have offsetting business expenses for it), respond with a Schedule C and supporting documentation. Many CP2000 cases resolve in the filer's favour when expenses are produced.

CP504 — Final notice before levy

A CP504 is a serious escalation: it is the final notice before the agency may levy state tax refunds, and it precedes (but is not the same as) the formal Final Notice of Intent to Levy under Internal Revenue Code §6330, which is the trigger for collection-due-process rights. Do not ignore it. Either pay, request a payment plan, or submit a Collection Due Process request — but address it within the stated window.

CP05 — Return is under review

Your return is being held for additional review, typically of credits, withholding, or income matching. No action is required from you unless a follow-up notice asks for documentation. The hold typically resolves within 60 days; refunds are released once the review completes.

What it is

An Identity Protection PIN is a six-digit number tied to your SSN that must be included on any federal individual return filed under that SSN. Without the correct PIN, a return is rejected at submission. The PIN is regenerated for each filing season and is delivered through your online account.

Who can opt in

The IP PIN programme is open to any taxpayer who can verify their identity online. There is no income limit and no eligibility restriction beyond identity verification. Filers who have previously been victims of return-related identity theft are enrolled automatically.

How to enroll

1. Sign in to your online taxpayer account using identity verification through the federal credential provider.
2. Navigate to the Profile section and choose Get an IP PIN.
3. Verify identity (photo ID upload + selfie, or video chat as a fallback). The PIN is displayed immediately on success.
4. Record the PIN in a secure location — you will need it for the upcoming season's return, and a request for a new one if lost involves a paper-form delay.

Using the PIN at filing

Tax software prompts for the IP PIN at the signature step. The PIN goes on the return for the filer, the spouse if filing jointly and they have one, and dependents if they have one. Paper filers enter the PIN on the appropriate line of the signature block.