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Tier-1 auto suppliers send semi-finished parts to deep sub-vendor tiers — plating, heat-treatment, machining, painting, anodising, phosphating — sometimes multi-hop across two or three job-workers before return, under Section 143 of the CGST Act with a one-year input return clock (three years for capital goods) beyond which the dispatch is deemed a supply with 18% interest; reconciling the challan-out register, the inter-job-worker movement challans, the physical-return GRN, the conversion-charge invoice with Section 393(1)(a) code 1002 TDS, and the quarterly ITC-04 is a multi-way control that breaks once monthly challan volume runs into the thousands.
Tag every Section 143 dispatch challan at origin with job-worker GSTIN, process type, input/capital-goods flag, quantity and a one-year (or three-year) statutory clock from the original dispatch date; track multi-hop parts across each inter-job-worker challan against the single original clock; match return GRN to dispatch on quantity within process-loss tolerance; price the conversion invoice against returned quantity and deduct Section 393(1)(a) TDS at 1% or 2%; roll open positions into the quarterly ITC-04; alert on challans approaching the statutory window.
Job-worker master with GSTIN, PAN, process type and Section 393 TDS rate; challan series per principal GSTIN; statutory clock per challan (1 year inputs, 3 years capital goods, none for jigs/fixtures/moulds/dies); multi-hop routing map per part; process-loss tolerance per process; conversion-charge rate card; ITC-04 quarterly due-date calendar; alert thresholds 60 and 30 days before the window.
A daily job-work dashboard showing open dispatches by job-worker and by hop, days remaining to the one-year window, return-versus-dispatch reconciliation within process-loss tolerance, conversion invoices matched to returned quantity with Section 393(1)(a) code 1002 TDS, and the quarterly ITC-04 position reconciled to the challan registers across the full multi-hop chain.
A Tier-1 transmission-parts supplier in Pune ships 5,000 semi-finished components a month out to sub-vendors: forgings to a machinist, machined parts to a heat-treater, treated parts to a plater, then back to the line. On 31 March the job-work register holds 1,940 open challans across 17 sub-vendors — and 23 challans have quietly crossed the one-year mark without a booked return. Under Section 143(3) of the CGST Act those dispatches are now deemed supplies, retrospectively dated, with 18% interest running from the original dispatch date. The exposure runs to several lakh in deemed GST plus interest, on parts the company still owns and that are physically sitting at hop two of a three-hop route. This is Tier 2 sub-vendor job work reconciliation auto India at real volume — multi-hop, multi-process, and unforgiving on the clock.
Quick reference
| Concept | Scheme / standard | Regulator / body | GST or TDS code |
|---|---|---|---|
| Inputs sent to job-worker | Section 143 CGST Act, Rule 45 challan | CBIC / GST portal | No GST on dispatch |
| Input return window | One year from original dispatch | CBIC | Deemed supply + 18% interest if missed |
| Capital goods return window | Three years from dispatch | CBIC | Jigs/fixtures/moulds/dies: no clock |
| Movement reporting | ITC-04 quarterly return | CBIC | Quarterly above ₹5 crore turnover |
| Conversion-charge TDS | Section 393(1)(a), code 1002 | Income Tax portal | 1% individual/HUF, 2% company/firm |
Why auto has such deep sub-vendor tiering
Few industries fragment processing as deeply as auto components. A single forged or cast part rarely becomes finished in one place. It is sent out for machining (turning, milling, grinding to tolerance), heat treatment (carburising, hardening, tempering, nitriding for fatigue and wear life), plating (zinc, nickel, chrome for corrosion protection), phosphating (a pre-paint conversion coating), anodising (for aluminium parts), and painting — each a specialist sub-vendor with dedicated equipment and environmental clearances the Tier-1 does not hold in-house. The Tier-1 owns the part throughout; the sub-vendors sell only their process.
That structure is exactly what Section 143 of the CGST Act is built for, but it also multiplies the reconciliation burden: every hop is a movement, every movement is a challan, every challan starts (or continues) a statutory clock, and every conversion invoice carries GST and Section 393(1)(a) TDS.
The Section 143 mechanism
Under Section 143, the Tier-1 (principal) dispatches inputs to a job-worker on a delivery challan under Rule 45 — no GST on the dispatch, ownership retained, the job-worker billing only its conversion charge. The trade-off is the return clock: inputs must return (or be supplied from the job-worker’s premises under Section 143(1)(b)) within one year; capital goods within three years; jigs, fixtures, moulds and dies carry no clock. Miss the window and Section 143(3)/(4) deem the original dispatch a supply on the dispatch date, with GST plus 18% interest under Section 50 from that date. The general single-hop version of this mechanism is covered in sub-contractor and job-work reconciliation under Section 143; this article goes after the auto-specific multi-hop complication.
Multi-hop job work: one clock, many movements
The auto-specific twist is the multi-hop route. A part goes machinist → heat-treater → plater → back, never returning to the Tier-1 between hops. Section 143 permits goods to move directly from one job-worker to another, but the one-year clock runs from the principal’s original dispatch date — not from each hop. So a part that spends four months at the machinist, three at the heat-treater, and stalls at the plater has only five months of headroom left on the original clock, regardless of how recently it reached the plater.
This breaks naive tracking. A system that resets the clock at each inter-job-worker challan will under-report deemed-supply risk and let parts age past one year undetected. The correct control threads every hop onto a single original-dispatch timeline per part, and surfaces the chain age, not the last-movement age. Each inter-job-worker movement is its own challan that the ITC-04 must capture, but they all answer to one clock.
ITC-04 reconciliation
ITC-04 is the quarterly return (annual for turnover up to ₹5 crore) reporting goods sent to and received back from job-workers. The reconciliation ties:
- the challan-out register — parts dispatched to each job-worker,
- the inter-job-worker movement challans for multi-hop legs,
- the challan-in register — parts physically returned, and
- the open balance per job-worker that feeds the ITC-04 line items (opening balance, sent, returned, supplied-from-premises, closing).
A divergence between the Tier-1’s challan registers and the filed ITC-04 is the primary statutory control. The single highest-priority alert is any open balance whose original-dispatch date is approaching the one-year window.
Section 393(1)(a) TDS on conversion charges
Plating, heat-treatment, machining, painting, anodising and phosphating are services. The conversion charge therefore attracts TDS under Section 393(1)(a) of the Income Tax Act 2025, payment code 1002 (which replaced legacy Section 194C) — 1% for individual/HUF job-workers, 2% for company/firm job-workers, applied to the conversion charge only (never the input value the Tier-1 already owns). Thresholds: ₹30,000 per transaction, ₹1 lakh aggregate per job-worker per year. The same invoice carries GST on the conversion service. A common reconciliation error is deducting TDS on a grossed-up figure that includes input value — the deduction base must be the service charge alone.
Cross-era note: invoices and Form 26AS data raised before 1 April 2026 carry the legacy 194C reference for code 1002; reconciliation against historical 26AS must keep the legacy cross-reference live for at least one full tax-year cycle.
The four-way match
The control that closes the rail ties four documents per job-work leg: the job-work challan (parts out), the physical-return GRN (parts back, with process applied), the conversion-charge invoice (billed service with GST and Section 393(1)(a) TDS), and the ITC-04 position. A clean match confirms sent-equals-returned within process-loss tolerance, the conversion invoice prices the returned quantity at the agreed rate, TDS is at the correct Section 393 rate, and the open balance feeding ITC-04 is accurate. Breaks point to short-returns, unbilled conversion, mis-applied TDS, or challans drifting toward the deemed-supply window.
Three-way matching for job-work returns
See how challan-out, return GRN and the conversion invoice tie together — and where short-returns and TDS-base errors hide.
Open the three-way matching guide →Worked example — 5,000 components/month across 3 job-workers
A Tier-1 sends 5,000 components a month through a three-hop route — machining (a company sub-vendor), heat treatment (a company sub-vendor), and plating (an individual proprietor) — on Section 143 challans:
- Dispatched to machinist (hop 1): 5,000 parts on 42 challans
- Machinist → heat-treater (hop 2): 4,960 parts (40 scrapped at machining as out-of-tolerance, booked as process loss within the 1% band)
- Heat-treater → plater (hop 3): 4,955 parts (5 cracked in quench)
- Plater → Tier-1 (return GRN): 4,948 parts (7 rejected at plating)
- Conversion invoices: machining at ₹38/part (company, 2% TDS), heat treatment at ₹22/part (company, 2% TDS), plating at ₹14/part (individual, 1% TDS)
The four-way match per hop: machining invoice prices 5,000 parts (the dispatched quantity it processed) at ₹38 = ₹1.90 lakh, Section 393(1)(a) TDS at 2% = ₹3,800; heat treatment 4,960 × ₹22 = ₹1.09 lakh, TDS 2% = ₹2,183; plating 4,955 × ₹14 = ₹69,370, TDS at 1% (individual) = ₹694. The yield reconciliation: 5,000 sent, 4,948 returned, 52 lost across three processes — within the cumulative process-loss tolerance, each loss reason-coded. The ITC-04 for the quarter rolls every hop onto the original-dispatch clock; with a full chain cycle time of about six weeks, none of the month’s parts approach the one-year window — but the control flags two legacy parts from a stalled programme batch still open at the heat-treater past ten months for immediate expedite.
How sub-vendor job work fits the wider auto stack
This rail sits inside the automotive component manufacturing reconciliation sub-pillar and the manufacturing pillar guide. Where the Tier-1 itself receives free-issue steel from the OEM, it is simultaneously a job-worker on the inbound side — see free-issue steel and skeleton scrap reconciliation. For the ITC-04 and Rule 45 source text see the GST portal.
What automated reconciliation changes
Manual sub-vendor job-work reconciliation across thousands of multi-hop challans is where deemed-supply exposures hide until an audit finds them. Purpose-built reconciliation software India tracks every challan on its original-dispatch clock across hops, runs the four-way match against process-loss tolerance, deducts Section 393(1)(a) code 1002 TDS at the correct per-vendor rate, and reconciles the open position into ITC-04 — alerting 60 and 30 days before any window. TransactIG carries 24+ industry presets including a configuration for multi-hop Section 143 job-work and ITC-04 reconciliation. Customer outcomes include match-rate improvement from 51% to 88%. Build is two-to-four weeks on AWS Mumbai (ISO 27001:2022). For the inbound match discipline see three-way matching software India.