Your supplier has a button on your invoice now. It says pending.

The phone call that started this

"Oh, those are still pending on my side," he said. "I'll get to them."

That was a steel supplier talking to a clerk I know, about twelve invoices worth a little over ₹31 lakh including tax. Every voucher clean. Every GSTIN checksummed. The 2B recon had flagged all twelve as missing, and the entire explanation fit in one sentence and a shrug. I have thought about that call more than any whitepaper on input credit, because it taught me where credit actually lives now: not in your voucher, not even in your supplier's filing, but in a button they haven't clicked.

The waiting room, drawn out

Before IMS, the mental model was simple: supplier files GSTR-1, lines land in your 2B. Now there is a room in between with three doors, and I draw it for every AP team I meet:

Place this next to the two pages it leans on: 1 vs 2B vs 3B for the map, the 2B checklist for the routine. IMS is the new middle box. Everything downstream of it inherits its moods.

Twelve lines, three fates

Back to the twelve. When the clerk finally got the supplier to open IMS on a shared screen, the lines split the way they almost always split. Seven were plain pending, the supplier just hadn't looked. Three were pending because the quantities on the GSTR-1 didn't match what the supplier's own dispatch team remembered, so someone kept deferring them. Two were rejected outright.

Seven got accepted on the call. Three took two more weeks and a revised filing. And here is the arithmetic I want you to sit with: of ₹31 lakh in purchases, roughly ₹5 lakh in ITC spent a month in limbo for want of seven mouse clicks. No fraud. No dispute. Just unclicked buttons and a clerk who checked IMS for the first time in October.

Pending is the dangerous fate precisely because it looks like nothing. No error, no notice, just an absence. A rejected line at least shouts. A pending line sits silent while your 16(4) clock ticks underneath it.

When the fault is yours

Those two rejected lines deserve their own section, because the ending surprised everyone. The supplier hadn't rejected them out of spite. Their GSTR-1 carried the buyer's GSTIN with two digits swapped, so to them those invoices looked like someone else's. Your own GSTIN discipline matters here in reverse. Read why we require the buyer GSTIN: the same digit string that gates your voucher is the string their filing must carry, and a transposition at their end reads as a rejection at yours.

So the rejection workflow I teach is: compare first, accuse never. Pull the rejected line, lay it next to your voucher, check buyer GSTIN, invoice number, FY. Fix your side where it is wrong, send the supplier specifics where it is theirs, and get the line re-furnished. Most rejections I have seen die at the comparison step because nobody put the two papers side by side.

And the boundary, stated plainly as always: our gate proves your document. IMS is the supplier's action on the portal. A voucher can pass checksum, HSN, arithmetic within ₹1, and regime, post to Tally, and sit pending for months. The gate did its job. The credit waits on a human clicking a button. Your process has to hold both halves, because no software holds them for you.

The Friday hour

If I ran your AP desk I would put one recurring hour on the calendar from the month GSTR-1 season opens. Friday, before filing week. Three jobs, same order every time.

First, list every pending line over two weeks old. Age is the signal. Fresh pending is normal. Stale pending is a supplier who forgot you, and the list is short enough to actually work through in an hour.

Second, chase largest-first in writing. A phone call gets a shrug; I know, I heard one. A mail with invoice number, date, and amount gets an action. Copy the trail into the voucher file. Your CA will bless you at scrutiny.

Third, re-pull before 3B. IMS moves after GSTR-1 due dates. A line pending on the 11th can be accepted on the 14th, and filing 3B off a stale pull leaves credit on the table that was already yours. The hour pays for itself the first month it catches one line.