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<title>W-2 Box 12 codes — audit your codes in browser</title>
<meta name="description" content="This free tool audits a payroll deduction code map for pre-tax flags, Box 12 letters, duplicate codes, and stale plan years, and names each broken line.">
<style>
:root{color-scheme:light}body{margin:0;font:15px/1.55 system-ui,-apple-system,"Segoe UI",sans-serif;background:#faf9f5;color:#1a1512}
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input[type=date]{font:14px system-ui;padding:8px;border:1px solid #d9d0c4;border-radius:6px}
table{border-collapse:collapse;width:100%;font-size:14px;margin-top:10px}th,td{text-align:left;padding:8px 10px;border-bottom:1px solid #eee;vertical-align:top}th{font-size:12px;letter-spacing:.06em;text-transform:uppercase;color:#7a6e65}
.sev.error{color:#a8551f;font-weight:700}.sev.warn,.sev.warning{color:#96691f}.ok{color:#2a6446;font-weight:600}.sum{font-weight:600}
.note{font-size:13px;color:#7a6e65;margin-top:18px}#paid{margin-top:22px;padding:14px 16px;border:1px solid #e2d8cb;border-radius:10px;background:#fffdfa}
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<h1>W-2 Box 12 codes — audit your codes in browser</h1>
<p class="lede">Audits a payroll deduction code map before January W-2 filing: pre-tax flags, Box 12 letters, duplicate codes, stale plan years. Every broken line is named with its line number. Runs entirely in your browser — nothing is uploaded.</p>
<textarea id="src" spellcheck="false">code,description,tax_treatment,plan_basis,box12,employer_amount,employee_amount,effective_date
401KEE,401(k) elective deferral,pre_tax,401k,D,0.00,250.00,2026-01-01
ROTH401K,Roth 401(k) deferral,pre_tax,401k,AA,0.00,150.00,2026-01-01
CHILDSUP,Child support withholding order,pre_tax,,,0.00,180.00,2026-01-01
DENTAL,Dental premium,,,,20.00,12.00,2026-01-01
HSAEE,HSA employee contribution,pre_tax,125,,,120.00,2026-01-01
FSAMED,Medical FSA,pre_tax,125,X,0.00,90.00,2026-01-01
TRANSIT,Qualified transit benefit,pre_tax,132,,0.00,80.00,2024-01-01
UNIFORM,Uniform purchase repayment,post_tax,,,0.00,25.00,
457BEE,457(b) elective deferral,pre_tax,457b,,0.00,200.00,2026-01-01
MEDPPO,Medical PPO premium,pre_tax,,,300.00,140.00,2026-01-01
MEDPPO,Medical PPO premium legacy,post_tax,,,300.00,140.00,2026-01-01</textarea>
<div class="bar"><button id="go">Check</button><label>as of <input type="date" id="today"></label></div>
<div id="out" aria-live="polite"></div>
<div id="paid"><strong>Free here:</strong> Every deduction code in the open map is audited against twelve rules and each broken line is named with its line number.. <strong>In the editor:</strong> Audits every deduction map in the workspace at once and writes a dated exposure report you keep as the payroll audit trail. — that part asks for a licence key.</div>
<p class="note">Same engine as the VS Code extension, byte for byte.</p>
</div>
<script>var PDCA_RULES = [
{"id": "roth_marked_pretax", "sev": "high", "msg": "Roth deferrals are always after-tax. This row is flagged pre_tax, so taxable wages come out low."},
{"id": "garnishment_pretax", "sev": "high", "msg": "Garnishments, child support and levies are withheld after tax. This row is flagged pre_tax."},
{"id": "missing_tax_treatment", "sev": "high", "msg": "tax_treatment is empty. Nothing in the map says whether this code reduces taxable wages."},
{"id": "duplicate_code_conflict", "sev": "high", "msg": "This deduction code already appears above with a different tax_treatment."},
{"id": "pretax_without_plan_basis", "sev": "med", "msg": "Pre-tax row names no plan_basis (125, 401k, 403b, 457b, 132), so nothing supports the exclusion."},
{"id": "bad_box12_letter", "sev": "high", "msg": "This box12 value is not an IRS W-2 Box 12 code letter."},
{"id": "deferral_without_box12", "sev": "med", "msg": "Elective-deferral code carries no W-2 Box 12 letter (D, E, G, S, AA, BB, EE)."},
{"id": "hsa_without_box12_w", "sev": "high", "msg": "HSA contributions report in W-2 Box 12 under code W. This row does not carry W."},
{"id": "hsa_no_employer_split", "sev": "med", "msg": "Box 12 code W is employer plus employee combined. This row has no employer_amount to add."},
{"id": "stale_plan_year", "sev": "high", "msg": "effective_date is older than the plan year being filed. Deduction limits reset every January 1."},
{"id": "missing_effective_date", "sev": "med", "msg": "effective_date is empty, so the row cannot be tied to a plan year."},
{"id": "no_withholding_order", "sev": "med", "msg": "A garnishment code is present but the map has no order column to rank it against other deductions."}
]
;</script>
<script>/* Payroll Deduction Code Audit — one brain, used by the VS Code extension and by the free web page. */
(function (root) {
'use strict';
var RULES = (typeof module !== 'undefined' && module.exports)
? require('./rules.json')
: (root.PDCA_RULES || []);
var RULE_BY_ID = {};
for (var r = 0; r < RULES.length; r++) { RULE_BY_ID[RULES[r].id] = RULES[r]; }
// IRS W-2 Box 12 code letters.
var BOX12 = ['A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','V','W','Y','Z',
'AA','BB','DD','EE','FF','GG','HH','II'];
var DEFERRAL_BOX12 = ['D','E','G','S','H','AA','BB','EE'];
var PLAN_BASIS = ['125','129','132','401K','403B','457B','408P','501C18D'];
var RE_ROTH = /roth/i;
var RE_GARNISH = /garnish|levy|child\s*support|childsup|chld|creditor\s*withhold/i;
var RE_DEFERRAL = /401\s*\(?k|401k|403\s*\(?b|403b|457\s*\(?b|457b|elective\s*deferral|deferral/i;
var RE_HSA = /\bhsa\b|health\s*savings/i;
function flat(s) { return String(s === undefined || s === null ? '' : s).replace(/\s+/g, ' ').trim(); }
function planYear(opts) {
var t = flat((opts || {}).today);
var m = t.match(/(\d{4})/); // tolerate 2026-09-19, 2026/09/19, "2026-09-19x"
var y = m ? parseInt(m[1], 10) : NaN;
if (!y || y < 1990 || y > 2999) { y = new Date().getFullYear(); }
return y;
}
function splitRow(line) {
var out = [], cur = '', q = false;
for (var i = 0; i < line.length; i++) {
var c = line.charAt(i);
if (c === '"') { if (q && line.charAt(i + 1) === '"') { cur += '"'; i++; } else { q = !q; } }
else if (c === ',' && !q) { out.push(cur); cur = ''; }
else { cur += c; }
}
out.push(cur);
for (var j = 0; j < out.length; j++) { out[j] = flat(out[j]); }
return out;
}
function norm(h) { return h.toLowerCase().replace(/[^a-z0-9]+/g, '_').replace(/^_|_$/g, ''); }
function check(text, opts) {
opts = opts || {};
var findings = [];
var year = planYear(opts);
var lines = String(text === undefined || text === null ? '' : text).split(/\r\n|\r|\n/);
function add(id, line, extra) {
var rule = RULE_BY_ID[id] || { id: id, sev: 'med', msg: id };
findings.push({ check: id, sev: rule.sev, msg: extra ? rule.msg + ' ' + extra : rule.msg, line: line });
}
// 1. locate the header row
var hIdx = -1, head = null;
for (var i = 0; i < lines.length; i++) {
if (!flat(lines[i])) { continue; }
var cells = splitRow(lines[i]).map(norm);
if (cells.indexOf('code') >= 0 || cells.indexOf('deduction_code') >= 0) { hIdx = i; head = cells; break; }
if (hIdx < 0 && i > 4) { break; }
}
if (hIdx < 0) { return { findings: findings, rows: 0, ruleCount: RULES.length, planYear: year }; }
function col(names) {
for (var n = 0; n < names.length; n++) { var k = head.indexOf(names[n]); if (k >= 0) { return k; } }
return -1;
}
var cCode = col(['code', 'deduction_code']);
var cDesc = col(['description', 'name', 'label']);
var cTax = col(['tax_treatment', 'tax', 'treatment', 'pre_tax']);
var cPlan = col(['plan_basis', 'plan', 'basis', 'plan_type']);
var cBox = col(['box12', 'w2_box12', 'box_12']);
var cEr = col(['employer_amount', 'employer', 'er_amount']);
var cEe = col(['employee_amount', 'employee', 'ee_amount']);
var cEff = col(['effective_date', 'effective', 'start_date']);
var cOrd = col(['order', 'priority', 'withholding_order', 'sequence']);
var seen = {}, rows = 0, sawGarnish = false;
for (var li = hIdx + 1; li < lines.length; li++) {
var raw = lines[li];
if (!flat(raw)) { continue; }
var f = splitRow(raw);
var get = function (k) { return k >= 0 && k < f.length ? f[k] : ''; };
var code = get(cCode);
if (!code) { continue; }
rows++;
var ln = li + 1;
var desc = get(cDesc);
var blob = code + ' ' + desc;
var tax = get(cTax).toLowerCase().replace(/[^a-z]/g, ''); // pre_tax -> pretax
var isPre = tax === 'pretax' || tax === 'pre' || tax === 'true' || tax === 'yes';
var plan = get(cPlan).toUpperCase().replace(/[^A-Z0-9]/g, '');
var box = get(cBox).toUpperCase().replace(/[^A-Z]/g, '');
var eff = get(cEff);
var garnish = RE_GARNISH.test(blob);
if (garnish) { sawGarnish = true; }
if (RE_ROTH.test(blob) && isPre) { add('roth_marked_pretax', ln, '(' + code + ')'); }
if (garnish && isPre) { add('garnishment_pretax', ln, '(' + code + ')'); }
if (!get(cTax)) { add('missing_tax_treatment', ln, '(' + code + ')'); }
var key = code.toUpperCase();
if (Object.prototype.hasOwnProperty.call(seen, key)) {
if (seen[key].tax !== tax) { add('duplicate_code_conflict', ln, '(' + code + ' first seen on line ' + seen[key].line + ')'); }
} else { seen[key] = { tax: tax, line: ln }; }
if (isPre && PLAN_BASIS.indexOf(plan) < 0) { add('pretax_without_plan_basis', ln, '(' + code + ')'); }
if (box && BOX12.indexOf(box) < 0) { add('bad_box12_letter', ln, '(' + code + ' carries ' + box + ')'); }
if (!box && RE_DEFERRAL.test(blob) && !RE_HSA.test(blob)) { add('deferral_without_box12', ln, '(' + code + ')'); }
if (RE_HSA.test(blob)) {
if (box !== 'W') { add('hsa_without_box12_w', ln, '(' + code + ')'); }
if (!get(cEr)) { add('hsa_no_employer_split', ln, '(' + code + ')'); }
}
var ym = eff.match(/(\d{4})/);
if (!eff) { add('missing_effective_date', ln, '(' + code + ')'); }
else if (ym && parseInt(ym[1], 10) < year) { add('stale_plan_year', ln, '(' + code + ' is dated ' + eff + ', plan year ' + year + ')'); }
void cEe; void DEFERRAL_BOX12;
}
if (sawGarnish && cOrd < 0) { add('no_withholding_order', hIdx + 1, '(header row has no order column)'); }
findings.sort(function (a, b) { return a.line - b.line; });
return { findings: findings, rows: rows, ruleCount: RULES.length, planYear: year };
}
var api = { engine: { check: check }, RULES: RULES, RULE_COUNT: RULES.length };
if (typeof module !== 'undefined' && module.exports) { module.exports = api; }
root.PDCAENGINE = api;
})(typeof window !== 'undefined' ? window : globalThis);
</script>
<script>// ⛔뼈대 — kit/scaffold.py 가 찍는다 (s143). findings [{check,sev,msg,line?}] → 글/HTML. 같은 파일이 Node 와 브라우저에서 산다.
'use strict';
function escapeHtml(s) { return String(s == null ? '' : s).replace(/&/g, '&').replace(/</g, '<').replace(/>/g, '>').replace(/"/g, '"'); }
function summaryLine(res) {
const f = (res && res.findings) || []; const e = f.filter(function (x) { return String(x.sev || 'error').toLowerCase().startsWith('err'); }).length;
return f.length ? (f.length + ' finding' + (f.length === 1 ? '' : 's') + ' (' + e + ' error' + (e === 1 ? '' : 's') + ')') : 'Clean — no findings.';
}
function toText(res, label) {
const f = (res && res.findings) || [];
const lines = ['== ' + (label || '') + ' — ' + summaryLine(res)];
f.forEach(function (x) { lines.push(' ' + String(x.sev || 'error').toUpperCase().slice(0, 4) + ' ' + (x.line ? 'L' + x.line + ' ' : '') + (x.check || x.id || '') + ' ' + (x.msg || x.message || '')); });
return lines.join('\n');
}
function toHtml(res) {
const f = (res && res.findings) || [];
if (!f.length) return '<p class="ok">' + escapeHtml(summaryLine(res)) + '</p>';
const rows = f.map(function (x) { return '<tr><td class="sev ' + escapeHtml(String(x.sev || 'error')) + '">' + escapeHtml(String(x.sev || 'error')) + '</td><td>' + (x.line ? 'L' + escapeHtml(x.line) : '') + '</td><td><code>' + escapeHtml(x.check || x.id || '') + '</code></td><td>' + escapeHtml(x.msg || x.message || '') + '</td></tr>'; }).join('');
return '<p class="sum">' + escapeHtml(summaryLine(res)) + '</p><table><thead><tr><th>Level</th><th>Line</th><th>Check</th><th>What</th></tr></thead><tbody>' + rows + '</tbody></table>';
}
var PDCAREPORT = { escapeHtml: escapeHtml, summaryLine: summaryLine, toText: toText, toHtml: toHtml };
if (typeof module !== 'undefined' && module.exports) module.exports = PDCAREPORT;
else window.PDCAREPORT = PDCAREPORT;
</script>
<script>
(function(){
var src=document.getElementById('src'), out=document.getElementById('out'), go=document.getElementById('go'), today=document.getElementById('today');
today.value=new Date().toISOString().slice(0,10);
function run(){ try { var res=window.PDCAENGINE.engine.check(src.value,{today:today.value}); out.innerHTML=window.PDCAREPORT.toHtml(res); } catch(e){ out.innerHTML='<p class="sev error">Could not run: '+String(e.message||e)+'</p>'; } }
go.onclick=run; if (src.value.trim()) run();
})();
</script>
<section data-yj-install="free" style="margin:2rem auto 1rem;max-width:46rem;padding:1.25rem 1.25rem;border:1px solid #cfe3d6;border-radius:12px;background:#f6fbf8;font:16px/1.6 system-ui,-apple-system,Segoe UI,sans-serif"><h2 style="margin:0 0 .4rem;font-size:1.2rem">Install free</h2><p style="margin:0 0 .8rem;color:#41505f">Free for the file open in your editor - no key, no limit. The workspace sweep and the report ask for a key.</p><a href="https://marketplace.visualstudio.com/items?itemName=ReadyStack.payroll-deduction-code-audit" rel="noopener" data-yj-install-door="mp" onclick="try{navigator.sendBeacon('/api/ev',new Blob([JSON.stringify({t:'install',slug:'payroll-deduction-code-audit',src:'mp',path:location.pathname})],{type:'application/json'}))}catch(e){}" style="display:inline-block;margin:0 .5rem .5rem 0;padding:.6rem 1rem;border-radius:8px;background:#0f7b3f;color:#fff;text-decoration:none;font-weight:600">VS Code Marketplace</a><a href="https://www.npmjs.com/package/@readystack/payroll-deduction-code-audit" rel="noopener" data-yj-install-door="npm" onclick="try{navigator.sendBeacon('/api/ev',new Blob([JSON.stringify({t:'install',slug:'payroll-deduction-code-audit',src:'npm',path:location.pathname})],{type:'application/json'}))}catch(e){}" style="display:inline-block;margin:0 .5rem .5rem 0;padding:.6rem 1rem;border-radius:8px;background:#0f7b3f;color:#fff;text-decoration:none;font-weight:600">npm</a><a href="https://www.npmjs.com/package/@readystack/payroll-deduction-code-audit" rel="noopener" data-yj-install-door="mcp" onclick="try{navigator.sendBeacon('/api/ev',new Blob([JSON.stringify({t:'install',slug:'payroll-deduction-code-audit',src:'mcp',path:location.pathname})],{type:'application/json'}))}catch(e){}" style="display:inline-block;margin:0 .5rem .5rem 0;padding:.6rem 1rem;border-radius:8px;background:#0f7b3f;color:#fff;text-decoration:none;font-weight:600">MCP server (npx)</a><a href="https://hub.docker.com/r/getreadystack/payroll-deduction-code-audit" rel="noopener" data-yj-install-door="docker" onclick="try{navigator.sendBeacon('/api/ev',new Blob([JSON.stringify({t:'install',slug:'payroll-deduction-code-audit',src:'docker',path:location.pathname})],{type:'application/json'}))}catch(e){}" style="display:inline-block;margin:0 .5rem .5rem 0;padding:.6rem 1rem;border-radius:8px;background:#0f7b3f;color:#fff;text-decoration:none;font-weight:600">Docker Hub</a><pre style="margin:.5rem 0 0;padding:.6rem .8rem;background:#f3f5f8;border-radius:8px;font-size:.9rem;overflow:auto">ext install ReadyStack.payroll-deduction-code-audit
npx @readystack/payroll-deduction-code-audit <file>
npx @readystack/payroll-deduction-code-audit --mcp</pre><p style="margin:.6rem 0 0;font-size:.92rem;color:#41505f"><a href="https://getreadystack.com/api/buy/team" rel="nofollow" style="color:#0f7b3f;text-decoration:underline">Team? One key for every ReadyStack linter, 5 seats, $149 once</a></p></section>
<section data-yj-alert="rule" style="margin:1rem auto 1.5rem;max-width:46rem;padding:1.1rem 1.25rem;border:1px solid #d9dee6;border-radius:12px;background:#fbfcfd;font:15px/1.55 system-ui,-apple-system,Segoe UI,sans-serif"><b style="font-size:1.05rem">Get the full rule table as a PDF</b><div style="opacity:.78;margin:.35rem 0 .8rem">All 12 rules Payroll Deduction Code Audit 2026 checks, each with its source and date, on printable pages you can hand to your team or auditor. We email it now, and once more only if a rule changes. No newsletter.</div><div style="display:flex;gap:8px;flex-wrap:wrap"><input id="yjae" type="email" placeholder="you@example.com" style="flex:1;min-width:210px;padding:11px 13px;border:1px solid rgba(140,150,165,.34);border-radius:8px;background:#fff;color:inherit"><button id="yjab" style="padding:11px 18px;border-radius:8px;border:0;cursor:pointer;background:#0f7b3f;color:#fff;font:600 15px system-ui,sans-serif">Email me the PDF</button></div><div id="yjao" hidden style="margin-top:.6rem;color:#0f7b3f">Sent. It arrives within the hour - check spam too.</div><script>(function(){var b=document.getElementById("yjab"),e=document.getElementById("yjae");if(!b||!e)return;b.addEventListener("click",function(){var v=e.value.trim();if(!/.+@.+\..+/.test(v))return;try{localStorage.setItem("yj_em","1");}catch(_){}fetch(location.origin+"/api/subscribe",{method:"POST",headers:{"Content-Type":"application/json"},body:JSON.stringify({email:v,slug:"payroll-deduction-code-audit",lang:"en",source:"rule_table"+((b.closest&&b.closest("section")&&b.closest("section").getAttribute("data-yj-moved"))?"_at_result":"")})}).then(function(r){var o=document.getElementById("yjao");o.hidden=false;if(!r.ok){o.textContent="Could not save - please try again.";}}).catch(function(){var o=document.getElementById("yjao");o.hidden=false;o.textContent="Could not save - please try again.";});});})();</script><script>(function(){var e=document.getElementById("yjae"),s=e&&e.closest?e.closest("section"):null,o=document.getElementById("out");if(!s||!o)return;var d=false;function mv(ev){if(d)return;if(ev&&ev.target&&s.contains(ev.target))return;d=true;var b=o;while(b.parentNode&&b.parentNode!==document.body&&b.parentNode.tagName!=="MAIN"&&b.parentNode.tagName!=="ARTICLE")b=b.parentNode;if(!b.parentNode||b===s||b.contains(s))return;try{b.parentNode.insertBefore(s,b.nextSibling);s.setAttribute("data-yj-moved","1");}catch(_){}}document.addEventListener("input",mv,true);document.addEventListener("change",mv,true);})();</script></section>
<section data-yj-cta="paid" style="margin:3rem auto;max-width:46rem;padding:1.5rem 1.25rem;border:1px solid #d8dee9;border-radius:12px;background:#fbfcfe;font:16px/1.6 system-ui,-apple-system,Segoe UI,sans-serif"><h2 style="margin:0 0 .5rem;font-size:1.25rem">Get the complete version <span class="yj-price">$29</span></h2><p style="margin:.25rem 0 1rem;color:#41505f">This page is the working piece. The full pack has everything below.</p><p style="margin:0 0 1rem;color:#41505f">Twelve rules over the deduction-code map, before the January 31 W-2 filing date</p><p style="margin:0 0 1rem;color:#5b6b7c;font-size:.94rem">Hand-checking one deduction map against the IRS Box 12 letter list is about half a day of a payroll analyst's time, every plan year</p><a href="https://getreadystack.com/api/buy/cl/polar_cl_nAgRlEvSuB50Wdx5AxIH3jJ7eqwgOTIAwUFRk26gtYC" rel="nofollow" style="display:inline-block;padding:.7rem 1.3rem;border-radius:8px;background:#1b64f2;color:#fff;text-decoration:none;font-weight:600">Buy the full version — $29</a></section>
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<p>The file those findings came from is the least-reviewed artefact in a payroll integration: the deduction code map. It is usually a CSV, usually checked into the same repository as the integration code, and it carries one row per deduction code with the columns that decide an employee's taxable wages — tax_treatment, plan_basis, box12, employer_amount, employee_amount, effective_date, order.</p>
<p>Nothing in that file is syntax. A row is valid CSV whether the tax flag is right or wrong. The schema validator passes it. The CI job passes it. The payroll engine reads it and quietly computes taxable wages from it, every pay period, for a year.</p>
<p>Here is what the audit found in the bundled sample map.</p>
<p>On line 3, a code named ROTH401K carried tax_treatment pre_tax. Roth deferrals are always after-tax; the pre-tax flag understates taxable wages on every pay run that uses it. On line 4, CHILDSUP — a child support withholding order — was also flagged pre_tax. Garnishments, child support and levies are withheld after tax, not before it. On line 5, DENTAL had no tax_treatment value at all, which means nothing in the map says whether that code reduces taxable wages.</p>
<p>Line 6 was an HSA row with an empty box12 column and no employer_amount. HSA contributions report in W-2 Box 12 under code W, and code W is employer plus employee combined, so the employer side has to be in the map or the Box 12 total is short. Line 7 carried a box12 value of X, which is not an IRS Box 12 letter. Line 8, TRANSIT, was dated 2024-01-01 and was still being read in plan year 2026 — deduction limits reset every January 1. Line 9 had no effective_date, so it ties to no plan year at all. Line 10, a 457(b) deferral, carried no Box 12 letter. Lines 11 and 12 were the same code, MEDPPO, once as pre_tax and once as post_tax, which makes the result depend on row order. And the map had no order column at all, so a garnishment code could not be ranked against the other deductions.</p>
<p>Thirteen findings. Ten deduction codes. One file that no test was ever going to fail on.</p>
<p>The reason this matters on a clock rather than someday is that a wrong deduction flag does not throw. It becomes visible when Forms W-2 go to employees and to the Social Security Administration by January 31. From there the remedy is a Form W-2c per affected employee, plus a re-run of the affected pay periods to find out what the right numbers were.</p>
<p>The clean sample map, 9 codes over 9 rows, returns 0 findings — which is the point. The audit is not a heuristic that flags everything; the same twelve rules that produced thirteen findings on the broken map produce silence on the correct one.</p>
<p>Doing this by hand is not impossible. It is about half a day of a payroll analyst's time to read one map against the IRS Box 12 letter list, row by row — and it has to happen again every plan year, because the map changes whenever a benefit is added.</p>
<p>The extension runs one command over the open file and names every broken line with its line number. The same engine file runs the free web page, so the map never leaves the machine either way. The full version widens the scope: every deduction map in the workspace at once, and a dated exposure report you keep as the payroll audit trail.</p></div><h2 style="font:600 21px/1.3 system-ui,sans-serif;margin:34px 0 6px;color:#1b1f24">Questions people ask</h2><details style="border-bottom:1px solid #e6e9ed;padding:10px 0"><summary style="cursor:pointer;font:600 15px/1.4 system-ui,sans-serif;color:#1b1f24">What does Payroll Deduction Code Audit actually do?</summary><p style="margin:8px 0 2px;font:400 14.5px/1.6 system-ui,sans-serif;color:#33404b">Twelve rules run over your deduction-code map: Roth flagged pre-tax, garnishment flagged pre-tax, missing tax treatment, duplicate code conflict, pre-tax without plan basis, invalid Box 12 letter, deferral without Box 12, HSA without code W, HSA without employer split, stale plan year, missing effective date, and missing withholding order. Each finding carries the line number.</p></details><details style="border-bottom:1px solid #e6e9ed;padding:10px 0"><summary style="cursor:pointer;font:600 15px/1.4 system-ui,sans-serif;color:#1b1f24">Who is this for?</summary><p style="margin:8px 0 2px;font:400 14.5px/1.6 system-ui,sans-serif;color:#33404b">Developers and payroll analysts in the United States who own the deduction-code map inside a payroll or HRIS integration — the CSV that maps internal benefit codes to tax treatment, plan basis and W-2 Box 12 letters. If you ship that file to ADP, Workday, Gusto or an in-house engine, this audits it.</p></details><details style="border-bottom:1px solid #e6e9ed;padding:10px 0"><summary style="cursor:pointer;font:600 15px/1.4 system-ui,sans-serif;color:#1b1f24">Why will a free tool not catch this?</summary><p style="margin:8px 0 2px;font:400 14.5px/1.6 system-ui,sans-serif;color:#33404b">Because nothing here is a syntax error. A deduction row is valid CSV whether the tax flag is right or wrong, so linters and schema validators pass it. A chatbot never sees your map file at all, and generic CSV checkers do not know which W-2 Box 12 letters the IRS accepts or that Roth is after-tax.</p></details><details style="border-bottom:1px solid #e6e9ed;padding:10px 0"><summary style="cursor:pointer;font:600 15px/1.4 system-ui,sans-serif;color:#1b1f24">What is free and what is in the full version?</summary><p style="margin:8px 0 2px;font:400 14.5px/1.6 system-ui,sans-serif;color:#33404b">Free: every deduction code in the open map is audited against all twelve rules, and each broken line is named with its line number. Nothing is locked, watermarked or time-limited. The full version audits every deduction map in the workspace at once and writes a dated exposure report you keep as the payroll audit trail.</p></details><details style="border-bottom:1px solid #e6e9ed;padding:10px 0"><summary style="cursor:pointer;font:600 15px/1.4 system-ui,sans-serif;color:#1b1f24">What would this cost with a person instead?</summary><p style="margin:8px 0 2px;font:400 14.5px/1.6 system-ui,sans-serif;color:#33404b">Hand-checking one deduction map against the IRS Box 12 letter list, row by row, is roughly half a day of a payroll analyst's time, and it has to happen again every plan year. If a wrong flag is only caught after the January 31 filing date, the work becomes a W-2c per affected employee plus a re-run of the affected pay periods.</p></details><details style="border-bottom:1px solid #e6e9ed;padding:10px 0"><summary style="cursor:pointer;font:600 15px/1.4 system-ui,sans-serif;color:#1b1f24">Why not just ask ChatGPT or another AI chat?</summary><p style="margin:8px 0 2px;font:400 14.5px/1.6 system-ui,sans-serif;color:#33404b">A general AI chat answers from training data with a cutoff date, cannot read your repository and names no rule version. Payroll Deduction Code Audit 2026 checks the file you open against 12 rules from a rule set dated 2026-09-20, and points at the exact line. For a filing, an audit or a client you need that dated result on your own files.</p></details><script type="application/ld+json" data-yj="yj-faq-ld">{"@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [{"@type": "Question", "name": "What does Payroll Deduction Code Audit actually do?", "acceptedAnswer": {"@type": "Answer", "text": "Twelve rules run over your deduction-code map: Roth flagged pre-tax, garnishment flagged pre-tax, missing tax treatment, duplicate code conflict, pre-tax without plan basis, invalid Box 12 letter, deferral without Box 12, HSA without code W, HSA without employer split, stale plan year, missing effective date, and missing withholding order. 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For a filing, an audit or a client you need that dated result on your own files."}}]}</script><div id="yj-ask" style="margin:36px 0 0;padding:18px 18px 16px;border:1px solid #e2e6ea;border-radius:10px;background:#fbfbfc"><h2 style="font:600 19px/1.3 system-ui,sans-serif;margin:0 0 4px;color:#1b1f24">Ask about this tool</h2><p style="font:400 13.5px/1.5 system-ui,sans-serif;margin:0 0 12px;color:#5b6570">One question, answered by the person who built it. 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