Sources & how we verify

Accuracy over completeness. A mapping ships as “verified” only when at least two independent published sources agree on it. Blog tables alone are not enough — and where sources disagree, the mapping is shown as unresolved or left out entirely, with the reason written down here.

Official sources

CBDT concordance — Form 121: the official section-wise concordance between the 1961 Act and the 2025 Act. (incometax.gov.in)
E-filing portal comparison utility: “Utility to check provisions of Income-tax Act, 1961 vis-à-vis Income-tax Act, 2025” — a two-way lookup, plus a Rules utility (1962 vs 2026) and a forms-mapping utility for the reduced 190-form set. (incometax.gov.in)

Published sources we checked

What we left out — and why

These mappings appear in one published table we checked, but we could not confirm them against a second independent source (or the sources conflict). We would rather have a smaller tool that is right than a complete one with a single wrong number. If you can confirm any of these against the CBDT concordance, tell us and we will add them.

Old section / form	Claimed new number	Why it is not in the tool
3	3	Only TaxGuru lists it; no second published source checked confirms Section 3 of the 2025 Act is the 'Tax Year' section. The Tax Year concept itself is confirmed by all sources — only the section number is left out.
6	6	Residential status — only one source (Durgesh Chavda) checked lists it.
13A, 14A, 15, 17, 22, 23, 25A, 26	12, 14, 15, 16, 17, 18, 20, 21, 23, 24	Salary and house-property detail rows — only TaxGuru checked lists them.
28, 29, 30, 32, 36, 37, 40, 40A, 43B, 41, 44AA	26, 27, 28, 33, 32, 34, 35, 36, 37, 38, 62	Business/profession computation rows — only TaxGuru checked lists them.
35	45	Scientific research expenditure — TaxGuru says 45, but TaxGuru itself notes another table says 135. Direct conflict, single source each side. Left out.
35AD	46	Specified business capex — only TaxGuru checked lists it.
45, 47, 48, 49, 50, 50B, 50C, 50CA, 55	67, 70, 72, 73, 74, 77, 78, 79, 90	Capital gains computation rows — only TaxGuru checked lists them.
56, 57, 58, 64, 68, 69, 69A, 69C, 69D	92, 93, 94, 99, 102, 103, 104, 105, 106	Other sources / clubbing / unexplained money rows — only TaxGuru checked lists them.
70, 71, 71B, 72, 73, 74, 78, 79, 80	108, 109, 110, 111, 112, 113, 119, 121	Set-off and carry-forward rows — only TaxGuru checked lists them. (Note: old 72→112 here is a different 112 from capital-gains 112→197; kept out to avoid any confusion.)
80A, 80CCH, 80DD, 80DDB, 80EE, 80EEA, 80EEB, 80GG, 80GGA, 80GGB, 80GGC, 80P, 80U, 80-IAC	122, 125, 127, 128, 130, 131, 132, 134, 135, 136, 137, 149, 154, 140	Chapter VI-A deduction rows beyond the most-used ones — only TaxGuru (and for 80-IAC only Durgesh Chavda) checked lists them.
87, 89, 90, 90A, 91	155, 157, 159, 160	Rebate framework / relief rows — only TaxGuru checked lists them.
115BAA, 115BAB	200, 201	Concessional company tax rates — only Durgesh Chavda checked lists them.
139A, 139B, 140, 140A, 140B	262, 264, 265, 266, 267	PAN / return verification / self-assessment rows — only TaxGuru checked lists them.
143(1)	270	Intimation after processing — only taxgst.in checked lists it.
148, 148A	280, 281	Reassessment notices — only Durgesh Chavda checked lists them.
197	395(1)	Lower / nil TDS certificate — only Durgesh Chavda checked lists it.
207–211	403–408	Advance tax liability / instalments — only Durgesh Chavda checked lists them.
234F	428	Late fee for delayed return — only Durgesh Chavda checked lists it.
270A	439	Penalty for under-reporting — only Durgesh Chavda checked lists it.
Form 10E	Form 123	Relief for salary arrears — only taxgst.in checked lists it.
Form 3CEB	Form 48	Transfer pricing report — only Durgesh Chavda checked lists it.
Form 10F	Form 41	Treaty relief details — only Durgesh Chavda checked lists it.
TCS codes 1068–1092	Section 394 table	Only the TaxGST.in rate-chart PDF checked lists the full TCS code set (1068 liquor, 1069 tendu leaves, 1070–71 timber, 1072 forest produce, 1073 scrap, 1074 minerals, 1075 motor vehicle, 1076–85 luxury goods, 1086–87 LRS, 1088–89 tour packages, 1090 parking, 1091 toll, 1092 mine/quarry). Rates are corroborated by CA Gaurav Verma, but the code numbers themselves have only one full published source. Left out of phase 1; needs a second source before shipping.
TDS code 1036	—	No published source checked assigns any payment to code 1036. It appears to be unassigned in the 1001–1067 range. Listed here so the gap is visible, not hidden.

Known conflicts we resolved by majority

Section 16 (standard deduction): majority says Section 19; one tracker says 22. Tool uses 19.
Section 24 (house property): majority says Section 22; one older tracker says 20. Tool uses 22.
44AD/44ADA/44AE (presumptive taxation): majority says Section 58; one source says 61. Tool uses 58.
Section 234A (late filing interest): majority says Section 423; TaxGuru notes a source saying 430. Tool uses 423.
Form 26AS: three sources say Form 168; one says Form 132. Tool uses 168.
Form 27EQ: majority says Form 143; TDSGuru says 144A. Tool uses 143.
TDS code 1012 (194LA): threshold ₹5,00,000 under the 2025 Act; one source still shows the old ₹2,50,000.
TDS code 1029 (194 dividend): threshold ₹10,000; one source still shows the old ₹5,000.