When you deposit a check through your banking app, the bank verifies it in layers: the app first checks that the photo is readable, then optical character recognition software pulls the routing number, account number, dollar amount, and endorsement off the image, and finally the data is run against fraud and duplicate-detection databases before the deposit is accepted. Most of this happens in seconds. Items that don’t pass automated screening get routed to a human reviewer, and even an accepted deposit keeps moving through interbank clearing in the background, which is why funds don’t always appear right away.
Here is what happens at each stage, and what causes a deposit to stall or get rejected.
What Happens the Moment You Snap the Photo
The verification process starts with image quality. Before the app tries to read anything on the check, it evaluates whether the photo is sharp enough to process. Blurry images, glare from overhead lighting, and shadows across the dollar amount or signature line are the common reasons an app refuses the capture and prompts you to retake it. Placing the check on a flat, dark surface in even, diffused light gives the software the contrast it needs to find the edges of the check and read the printed fields.
Once the image clears that threshold, the software focuses on the Magnetic Ink Character Recognition line printed along the bottom edge. The MICR line carries three pieces of data: a nine-digit routing number identifying the issuing bank, the account number holding the check writer’s funds, and the individual check number. The OCR software has to read the distinctive MICR font from a photograph rather than with a traditional magnetic reader, so a smudge, fold, or tear along the bottom edge of the check will usually cause the deposit to be rejected outright.
What the System Matches on the Check
With the MICR data captured, the software moves to the fields that confirm the check is valid and payable to you.
The dollar amount is read twice. The OCR captures the numerical amount in the small box (the courtesy amount) and the amount written out in words on the line below, then compares them. When the two disagree, the Uniform Commercial Code provides that the written words take priority over the numbers.1Cornell Law School. Uniform Commercial Code 3-114 – Contradictory Terms of Instrument In practice, most banks reject a mismatched check through mobile deposit rather than try to resolve it automatically.
The back of the check is scanned for two things. The first is your endorsement signature. Under the UCC, a person is not liable on a check unless they signed it, which is why the payee’s signature is a hard requirement; a missing signature means a rejected deposit.2Cornell Law School. Uniform Commercial Code 3-401 – Signature The second is a restrictive endorsement, usually something like “For Mobile Deposit Only” or “For Mobile Deposit at [Bank Name] Only.” That language gives the bank legal protection under Regulation CC if someone later tries to deposit the same paper check at another institution.3eCFR. 12 CFR Part 229 – Availability of Funds and Collection of Checks (Regulation CC) Many banks reject deposits where that restrictive language is missing.
The front of the check is checked against your account. The name on the “pay to the order of” line has to match the name on the account you’re depositing into. A check made out to Jane Smith can’t be deposited into John Smith’s account through mobile deposit, and third-party checks, where someone endorses a check over to you, are generally not accepted this way at all.
Fraud Screening and Duplicate Detection
After the data is extracted, the bank runs it through external fraud databases. Services such as Early Warning Services provide financial institutions with real-time information about the account that issued the check, including whether it is closed, has a history of returned items, or has been flagged for suspicious activity.4Consumer Financial Protection Bureau. Early Warning Services, LLC Depending on what the database returns, the bank may accept the deposit, reject it, or accept it with a hold on the funds.
The system also compares the check’s visual layout against known templates for that bank’s check stock. If the font, logo placement, or security features don’t match what the issuing bank’s checks should look like, the item gets flagged as a possible counterfeit before it ever reaches clearing.
Then there’s duplicate detection. The system logs the unique combination of routing number, account number, and check number for every deposit. If that combination has already been deposited at your bank or reported by another institution, the deposit is blocked. This is the layer that stops someone from depositing the same check twice across different banks, or depositing it through the app and then taking the paper original to a branch.
When a Human Reviewer Steps In
Software handles most deposits, but certain conditions push a check into a queue for manual review.
The most common trigger is low OCR confidence. When messy handwriting on the written-amount line makes the software uncertain about the intended value, a bank employee compares the check image to the extracted data and confirms or corrects the reading.
Unusually large deposits get flagged too. If your account normally sees checks for a few hundred dollars and a $10,000 item comes through, a reviewer examines the check for signs of physical alteration: erased ink, mismatched fonts, or areas where the paper looks scraped or chemically treated.
Checks approaching the six-month staleness threshold also get a closer look. An item four or five months old might clear automated screening but still be pulled for review, with the reviewer weighing the risk that the issuing bank will refuse to honor it.
Checks That Won’t Pass Verification
Some paper payments can’t be verified through mobile deposit at all, no matter how clean the photo is:
- Checks drawn on banks outside the United States, which require a different clearing process.
- Money orders and traveler’s checks, which have security features mobile systems aren’t built to process.
- U.S. Savings Bonds, which have to be redeemed through specific channels.
- Post-dated checks, because the funds aren’t yet authorized for withdrawal.
- Stale-dated checks. Under the UCC, a bank has no obligation to honor a personal or business check presented more than six months after its date, and mobile deposit systems typically flag or reject checks older than 180 days.5Cornell Law School. Uniform Commercial Code 4-404 – Bank Not Obliged to Pay Check More Than Six Months Old
- Checks that were previously deposited and returned unpaid, which can’t be resubmitted through the app.
For any of these, you’ll need to visit a branch or use a different payment method.
After “Deposit Accepted”: Holds and Funds Availability
Verification doesn’t end when the app tells you the deposit was accepted. The check continues through interbank clearing, and federal rules under Regulation CC set the minimum timeline for making the funds available.3eCFR. 12 CFR Part 229 – Availability of Funds and Collection of Checks (Regulation CC)
For most check deposits that don’t qualify for next-day availability, the bank has to make at least the first $275 available by the next business day. The rest typically becomes available by the second business day, though your bank’s policy may be faster. Some check types, such as U.S. Treasury checks deposited by the payee, qualify for full next-day availability regardless of how they were deposited.6eCFR. 12 CFR 229.10 – Next-Day Availability
Banks can extend hold times beyond that baseline under specific circumstances called exception holds. The common triggers are:
- Deposits exceeding $6,725. The first $6,725 still releases on the normal schedule; the excess can be held several additional business days.7Consumer Financial Protection Bureau. Availability of Funds and Collection of Checks (Regulation CC) – Threshold Adjustments
- Accounts open less than 30 days, where the bank can hold most deposited funds for up to nine business days.8Federal Reserve. A Guide to Regulation CC Compliance
- Repeatedly overdrawn accounts: a negative balance on six or more banking days in the past six months lets the bank apply extended holds.8Federal Reserve. A Guide to Regulation CC Compliance
- Reasonable doubt about collectibility, such as information that the issuing account has insufficient funds.
- Redeposited checks, which can be held longer on the second attempt.
When the bank places an exception hold, it has to notify you of the reason and when the funds will become available.
What to Do With the Paper Check Afterward
Even after the deposit is accepted and the funds have cleared, you still have the original paper check. Don’t destroy it right away. Most banks recommend holding onto it in a secure location for at least 30 days after the deposit posts, which is enough time for the check to fully clear and for any return, such as insufficient funds, to come back through the system.
Once that window has passed and the funds are settled, shred the check. A cross-cut shredder is the right tool because it destroys the account numbers and routing information on both your endorsement and the issuer’s side. Never try to deposit the same check again at a branch, an ATM, or through another bank’s app. The duplicate-detection layer described above will catch it, and some banks will close an account over a suspected duplicate deposit.