Taxes
Filing, withholding, quarterly estimates — Form 1040 line by line.
US federal tax filing for W-2 employees, 1099 contractors, and the gig economy. Form 1040 mechanics, quarterly estimated taxes, standard versus itemized deduction math, and the credits and deductions worth knowing before tax season.
The US federal tax system is large, dense in jargon, and surrounded by paid-tax-prep marketing that overstates the complexity for the typical case. For a substantial majority of US households — single W-2 wage earners with no dependents, married couples with combined W-2 income and no complicated investments, retirees on Social Security plus modest investment income — the actual annual tax return takes thirty to sixty minutes to complete and costs nothing if filed through one of the federally-supported free options. The fear of the IRS is much larger than the actual annual task for most households.
This section covers the practical mechanics of filing US federal taxes: how Form 1040 actually works, the difference between W-2 and 1099 income and the additional paperwork that 1099 income requires, the standard versus itemized deduction decision (the standard wins for over 90% of US filers since the 2017 tax law), the credits and deductions worth knowing before tax season, the quarterly estimated tax system that self-employed workers and substantial-investment-income filers need to navigate, and the free-filing pathways the IRS, state revenue departments, and certain nonprofit programs make available at no cost.
Two structural facts anchor every guide in this section. First, the federal income tax is a pay-as-you-go system. Withholding on W-2 paychecks (or quarterly estimated payments for 1099 income) is the prepayment toward annual tax liability. The annual return is the reconciliation — a refund means you over-prepaid, a balance owed means you under-prepaid. Large refunds are not free money; they are your own money returned because too much was held back during the year. Adjusting W-4 withholding to land closer to neutral keeps the cash in your hand throughout the year rather than as a lump sum in April. Second, the IRS supports several free filing pathways. The IRS Free File program (for adjusted gross income of $89,000 or less), the Volunteer Income Tax Assistance program (free in-person help for moderate-income filers), and Free Fillable Forms (for higher-income filers comfortable doing the math themselves) cover the vast majority of typical filing situations. The paid products (TurboTax, H&R Block at retail, professional preparers) are appropriate for genuinely complex returns but unnecessary for the typical W-2 employee.
What this section will not do is publish state-by-state filing guides (50 separate state tax systems is more than we can responsibly cover) or specific tax-advice recommendations for individual returns. Filing position, deduction eligibility, credit qualification, and entity choice depend on facts specific to each filer's situation that a published guide cannot address. The guides explain the federal system in general; for decisions on a specific return, an enrolled agent, CPA, or attorney is the right resource.
All articles in the taxes hub are written and edited by Cristian Corrales. Quantitative claims are anchored to primary US sources (CFPB, FDIC, FRB, IRS, FICO, FINRA, SEC, NCUA). Where the subject benefits from licensed review, a named US CFP, CPA, or attorney reviews before publication — editorial policy.
Start here
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Filing US taxes for the first time — Form 1040 line by line
How to file a federal tax return as a first-timer: W-2 vs 1099, standard vs itemized, refund mechanics, deadlines, free filing options.
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AGI on Form 1040 — line by line, with Schedule 1 in plain English
Every income line (1a–8) and every Schedule 1 adjustment that brings total income down to AGI on line 11 — the figure most credit and deduction phase-outs actually test against.
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Quarterly estimated taxes — the 1099 worker survival guide
Safe-harbor rules, Form 1040-ES, the four payment dates, underpayment penalty, what to do if you missed a quarter.
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Schedule SE — the 15.3% self-employment tax explained line by line
How Schedule SE actually computes the tax, where the deductions sit, the Social Security wage base ceiling, and the additional Medicare surcharge.
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Form W-4 — the withholding math that prevents April surprises
The 5 steps mapped to actual brackets, why dual-earner default under-withholds, and how to dial the W-4 to within $500 of zero at filing time.
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S-corp election for the self-employed — when the SE tax math works
How the salary + distribution split cuts the 15.3% SE tax, the reasonable-salary IRS standard, two worked examples ($150K consultant, $80K freelancer), and the QBI interaction.
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FICA payroll taxes — Social Security, Medicare, and the surtaxes above
The 6.2% OASDI portion up to the wage base, the 1.45% Medicare uncapped, the 0.9% Additional Medicare above ACA thresholds, and the self-employed SECA equivalent.
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Section 199A QBI deduction after OBBBA — the 20% pass-through math
How the qualified business income deduction works now that OBBBA made it permanent: the 20% math, the new $400 minimum, the 2026 thresholds, the W-2 wage limit, and the SSTB phase-out.
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MAGI — the number behind every tax phase-out
How modified adjusted gross income works: each MAGI variant, the add-backs that differ by provision, and the levers that move it.
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Saver's Credit — the most overlooked retirement tax break
How the Saver's Credit works: 10–50% of retirement contributions, who qualifies, the income thresholds, and how to claim it on Form 8880.
Side-by-side
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Standard deduction vs itemizing — when the math tilts each way
The mechanics, the SALT cap, the itemizing thresholds, and worked examples for both. Post-TCJA, ~90% take standard — here is when itemizing still wins.
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HDHP vs PPO — the premium-deductible math, with HSA
How to compare an HDHP against a PPO: premium savings, deductible risk, out-of-pocket caps, and the HSA tax advantage that tilts the math.
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HSA vs FSA — which pre-tax health account is yours
One is portable, invests, and rolls over; the other is the employer's and expires. The 2026 limits, the HDHP gate, and the Limited-Purpose FSA combo that runs both.
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The estimated-tax safe harbor — how much to pay to skip the penalty
Pay 90% of this year or 100% of last year (110% above $150K AGI) and the underpayment penalty cannot touch you, whatever the final bill. With a worked example.
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Your W-2 doesn't show AGI — how to build line 11 from it
Box 1 is taxable wages, not adjusted gross income. The W-2-to-Form-1040 walkthrough: line 9, the Schedule 1 adjustments, and a worked example landing on line 11.
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QCDs — give from your IRA, skip the tax entirely
From age 70½, up to $111,000 a year (2026) can travel from an IRA straight to charity without touching your AGI — stronger than a deduction, and from 73 it satisfies the RMD.
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HSA for the self-employed — the deduction works, the FICA break doesn't
No employer needed: the above-the-line deduction and the 2026 limits stand. What changes is FICA — payroll contributions skip the 7.65%, yours don't. The honest math, worked.
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The kiddie tax — when a child's income is taxed at your rate
In 2026 a child's unearned income above $2,700 is taxed at the parent's marginal rate on Form 8615. The three-tier thresholds, a worked $4,000 example, and the custodial-Roth and 529 levers that defuse it.
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How to file a tax extension — Form 4868 and the Oct 15 date
Form 4868 buys six months to file, to October 15 — but not to pay. The failure-to-file penalty is ten times the failure-to-pay penalty, so always file on time even when you cannot pay. A worked $5,000 example across three choices.
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Form 8949 column (f) codes — the adjustment-code cheat sheet
Every column (f) adjustment code in plain English, the column (g) sign rule that trips up investors, and a worked wash-sale (code W) example. The form mechanics, not the rates.
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Form 8889 line by line — the HSA deduction without the line-9 trap
Why W-2 box 12 code W goes on line 9 not line 2, the 2025 contribution limits, the per-person catch-up, and the path down to the deduction on Schedule 1, line 13.
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The HSA last-month rule and its 13-month testing-period trap
Fund the full year limit even if eligible only part of the year — but a lapse before December 31 of the next year claws it back with a 10% tax. The dates, the math, and the prorate opt-out.
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Form 2210 Schedule AI — annualize income to kill the penalty
The default penalty assumes even income. Schedule AI matches each installment to when you actually earned it, with the fixed 4/2.4/1.5/1 multipliers and the all-or-nothing trap.
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Form 1099-INT box by box — where each box lands on your return
Box 1 and box 3 both become taxable interest, but box 3 Treasury interest is exempt from state tax; box 2 is a separate Schedule 1 deduction; box 8 never touches Schedule B. The full routing map.
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1099-DIV box 1a vs 1b vs 2a — ordinary, qualified, capital gains
Box 1b is a slice of box 1a, never an addition to it; box 2a is a separate bucket of long-term gain that can skip Schedule D for Form 1040 line 7. The three-number relationship, decoded.
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Form 1099-B to Form 8949 — covered, noncovered, and Box A–F
How the box 12 basis-reported check plus the holding period decide which of the six Form 8949 category boxes a sale lands in, and when you override the broker's basis.
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When is Schedule B required? The $1,500 rule and seven more
You file when taxable interest or ordinary dividends top $1,500 — each tested separately — plus seven other triggers, including nominee income, the savings-bond exclusion, and the foreign-account question.
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How the Form 2210 underpayment penalty is actually calculated
The estimated-tax penalty is quarterly interest, not a flat fine: the 2026 rates, the $1,000 floor, the 90/100/110 safe harbors, and why the timing of each payment matters.
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Form 8960 line by line — the 3.8% net investment income tax
The 3.8% surtax hits the smaller of net investment income or MAGI over the $200k/$250k/$125k non-indexed thresholds. What counts, what does not, and the line-by-line flow.
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The Saver's Match replaces the Saver's Credit in 2027
From 2027, SECURE 2.0 turns the Saver's Credit into a 50% federal match deposited straight into your retirement account — up to $1,000. The statutory income bands.
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2027 tax brackets and standard deduction — the projection
The 2026 brackets and standard deduction are confirmed; how the 2027 figures are projected by chained-CPI indexing, clearly labeled, pending the IRS October release.
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2027 IRMAA brackets — the Medicare surcharge projection
Your 2027 Medicare surcharge is set by your 2025 income via the two-year lookback. The confirmed 2026 brackets, the cliff, and a clearly labeled 2027 projection.
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The 2027 Social Security wage base projection
The 2026 wage base is $184,500; the Trustees project $190,200 for 2027 (wage-indexed). What the cap taxes, what it does not (Medicare), and when it is official.
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The 2027 health FSA contribution limit projection
The 2026 health FSA limit is $3,400. Indexed and rounded to the nearest $50, the 2027 cap projects to a narrow $3,450-$3,500 range, confirmed by the IRS in the fall.
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HSA contribution limits 2027 — official, per Rev. Proc. 2026-24
The IRS already set the 2027 HSA limits in May: $4,500 self-only, $9,000 family. The HDHP thresholds, the $1,000 catch-up that never changes, and the new DPCSA rule.
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Social Security tax thresholds — $25,000/$32,000, frozen since 1984
The thresholds that make Social Security taxable have never been indexed for inflation. The two-tier math of 26 U.S.C. 86, worked examples, and the tax torpedo.
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W-4V vs W-4P — withholding on Social Security and pensions
Social Security withholding is a fixed menu of four rates on Form W-4V; pensions use Form W-4P and its steps. Which form covers which income, and where each one goes.
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W-2 Box 12 codes, A to II — what each one means on your 1040
Every Box 12 code from the official 2026 IRS instructions, including the new TP and TT codes for tips and overtime — and which ones actually change your return.
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Form 5498 — why it arrives in May and what to do with it
The IRA information form that shows up after the filing deadline by design. Box by box: contributions, rollovers, conversions, year-end value, and when to actually act.
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The 2027 401(k) and IRA limit projection — the statutory math
Applying the formula in 26 U.S.C. 402(g)(4) to CPI data: $25,000 or $25,500 for the 401(k), $8,000 for the IRA — and the exact summer CPI threshold that decides it.
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2027 estate and gift tax exemption — the projected numbers
OBBBA made the $15M per-person estate and gift exemption permanent from 2026, indexed from 2027. The projected 2027 figure, the $19,000 annual gift exclusion, and why the sunset never came.
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When your 1098-T box 5 exceeds box 1 — how much is taxable
Box 5 minus box 1 is not your taxable scholarship. The Pub 970 Worksheet 1-1 walkthrough, why room and board breaks the gap, and the American Opportunity Credit trade-off.
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Form 8606 line 14 — when you have lost track of your IRA basis
The basis carryforward chain from line 14 to next year's line 2, how to reconstruct lost basis from Form 5498 and IRS transcripts, and the $50 penalty you can usually waive.
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Form 8880 line 4 — the distribution that can erase your Saver's Credit
The testing-period distributions that reduce the credit, the exceptions that do not count, and why line 4 matters most in the final years before the 2027 Saver's Match.
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W-2 box 12 code V — fix the cost basis the broker got wrong
Code V is the stock-option spread already taxed in box 1, yet the 1099-B leaves it out and overstates your gain. The Form 8949 fix: code B in column (f) and a negative column (g) adjustment.
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Form 8962 line 5 — your percentage of the poverty line
The line says drop the decimals, not round, so 399.9% becomes 399. Why that one digit now flips your premium tax credit to zero in 2026, after the enhanced-subsidy cliff returned.
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Do both spouses file Form 709 when splitting a gift?
Usually yes, but two narrow exceptions let only the giver file while the other consents. The 2026 $19,000/$38,000 thresholds, the three scenarios, and the Notice of Consent.
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SSA-44 for a work stoppage — lower your IRMAA after retiring
A Medicare surcharge set by two-year-old income can be appealed when you retire. The fixed list of life-changing events, Step 2 vs Step 3, and the self-statement option.
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A 1099-C after a charge-off — when canceled debt is not taxed
A 1099-C is not an automatic tax bill. The insolvency exclusion on Form 982 line 1b often zeroes it out — the smaller-of rule, a worked insolvency worksheet, and the 36-month myth the IRS removed in 2016.
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Medicaid waiver payments (Notice 2014-7) — the new reporting path
Tax-free under Notice 2014-7, but the mechanic changed: W-2 box 1 to line 1a, box 12 code II to line 1d, and a negative on Schedule 1 line 8s. Plus the Earned Income Credit choice.
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Excess Social Security tax from two employers — Schedule 3 line 11
Two jobs can withhold past the annual cap. The refundable credit on Schedule 3 line 11, the 2024–2026 maximums, and why one employer over-withholding needs Form 843 instead.
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SSA-1099 lump-sum election — taxing Social Security back pay
A retroactive disability or retirement check crammed into one year can be taxed as if received across the prior years — no amended returns, just the Form 1040 line 6c election and Publication 915.
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Form 8959 — the 0.9% Additional Medicare Tax, reconciled
The 0.9% surtax hits earnings above $200k/$250k/$125k, but employers withhold on any single job over $200k regardless of filing status. Form 8959 settles the mismatch — refunding over-withholding, billing the two-job gap.
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Form 5329 — missed your RMD? Cut the penalty to 10% or zero
SECURE 2.0 dropped the missed-RMD excise from 50% to 25%, and to 10% if you correct it inside the window. The Part IX mechanics and the reasonable-cause RC waiver that can erase it entirely.
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Form 8995 — the simplified QBI deduction, line by line
The one-page route to the 20% pass-through deduction when 2026 taxable income is at or below $201,750 single / $403,500 MFJ. The lesser-of computation, the capital-gains ceiling, and the OBBBA $400 floor.
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Form 8915-F — disaster distributions and the 3-year spread
Up to $22,000 per disaster, no 10% penalty, income split over three years, and a 3-year-and-1-day window to repay and claw the tax back. Why the $100,000 figure people remember belongs to 2020 CARES.
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Schedule D Tax Worksheet — when lines 18 and 19 take over
An amount on Schedule D line 18 or 19 swaps the friendly 0/15/20 worksheet for the long one. Collectibles, QSBS, and depreciated real estate — and why the 25% and 28% rates are ceilings, not flat charges.
What changed recently
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2027 401(k) & IRA contribution limits: projections vs 2026
With 2026 limits confirmed (401k $24,500, IRA $7,500), here are the 2027 401(k), IRA, and Roth projections and the IRS rounding math behind each one.
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Tax season prep — the year-round runway to file confidently
A month-by-month checklist for the months before tax-filing season opens — what to organize, verify, and plan so you file confidently and capture deductions.
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The 0% capital gains bracket — the planning lever most filers miss
For single filers under ~$49K and couples under ~$99K of taxable income, long-term capital gains are taxed at 0% federal. The structural mechanics.
More in news and analysis.
Vocabulary for this topic
- AGI (Adjusted Gross Income) Total income minus specific above-the-line deductions — the basis for most downstream credit and deduction phase-outs.
- MAGI (Modified Adjusted Gross Income) AGI plus a set of add-backs that varies by tax provision — the gating number for Roth contribution and several credits.
- Standard deduction The flat deduction from AGI ~90% of US households take instead of itemizing post-TCJA.
- SALT cap The $10,000 limit on combined state and local taxes deductible on Schedule A — the structural break on itemizing in high-tax states.
- Form 1040 The federal individual income tax return — the form every US filer uses.
- Additional Medicare Tax The 0.9% surtax on wages and SE income above filing-status thresholds — non-indexed since 2013.
- OASDI wage base The annual ceiling on wages subject to Social Security tax — $176,100 in 2025, adjusted yearly.
- NIIT The 3.8% net investment income surtax above $200K single / $250K joint MAGI — non-indexed since 2013.
- QBI deduction The up-to-20% pass-through deduction under Section 199A — made permanent by OBBBA, with a new $400 floor for 2026.
Frequently asked
Does finbarrow do my taxes for me?
No. finbarrow is editorial — we explain how the federal tax system works, what forms apply to which situations, and what free-filing options the IRS supports. The actual return is filed by you through one of the free options (IRS Free File guided software for adjusted gross income of $89,000 or less, or Free File Fillable Forms above that) or through a paid product or professional preparer if your situation warrants. Note that IRS Direct File, the file-directly-with-the-IRS pilot, was discontinued and is not available for the 2026 filing season. The guides walk through the choice.
Do I need to file if my income is below the standard deduction?
Generally no, but yes if you had federal income tax withheld from a W-2 paycheck and want the refund, if you qualify for refundable credits (Earned Income Tax Credit, Premium Tax Credit), or if you had self-employment income above $400. The filing thresholds are published by the IRS each year and depend on filing status and age. When in doubt, filing is the safer default because not filing forfeits any refund you would have received.
How do quarterly estimated taxes work if I have both W-2 and 1099 income?
The W-2 withholding counts toward your total tax liability for the year, and your quarterly estimated payments cover the gap on the 1099 portion. Many filers in this situation increase their W-2 withholding (via Form W-4) instead of making quarterly payments, which is administratively simpler — additional withholding is treated as paid evenly across the year and avoids any underpayment penalty regardless of when it actually went in. Whether to use W-4 adjustment or quarterly payments depends on whether you can predict your 1099 income early in the year.
Is finbarrow giving me tax advice?
No. Every article in this section is educational. Filing position, deduction eligibility, credit qualification, and entity choice depend on your specific financial situation, state of residence, and other facts. The guides explain how the federal system works in general; for decisions on your specific return, consult an enrolled agent, CPA, or attorney. For simple W-2 returns, the IRS-supported free filing options walk you through the questions one at a time without needing outside advice.
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