You got a CBP bond insufficiency letter. Here's what to do before the deadline.
CBP's Revenue Division sends this letter automatically once its ACE sufficiency review finds your continuous bond's penal sum too small for the duties, taxes, and fees you've actually been paying. The letter itself states your deadline and the new minimum amount — do these four things in order, starting with reading the letter correctly.
Do these 4 things now
- 1Find the date printed at the top of the letter. Your response window counts from that date, not the day you opened the mail. See “What the deadline actually means” below.
- 2Start the replacement bond application today — don't wait to double-check the number. The letter already states CBP's required minimum.
- 3Flag any shipments landing before the new bond is active. Ask about a same-day single-transaction bond to bridge those specific entries — CBP's own Directive 3510-004 names this as an approved option.
- 4Don't let anyone terminate your old bond early without a replacement ready. A bond under an active insufficiency letter doesn't qualify for CBP's gap-free termination swap — see the cascade timeline below.
- Who requires it: CBP's Revenue Division, after an automated ACE sufficiency review.
- Amount: Continuous (Activity Code 1) bonds are priced at 10% of the duties, taxes, and fees paid in the lookback period, with a $50,000 floor (CBP Directive 3510-004).
- Shipments landing before the new bond is active can be bridged with a single-transaction bond, which Directive 3510-004 names as an approved option.
What the deadline actually means
Every insufficiency letter states its response deadline, and importers get this wrong constantly: 19 CFR 113.13(c) gives the principal 15 days from the date of notification to remedy the deficiency (follow any date stated on your letter), and the count starts from the date printed at the top of the letter, not the date you received or opened it. If your mail sat unopened for four days, you don't get those four days back.
The letter is issued by CBP's Revenue Division after an automated sufficiency review in the ACE system compares your bond's penal sum against the duties, taxes, and fees you've actually paid CBP as importer of record. There are two things that trigger this review: your duty volume outgrowing your bond's capacity, or money you owe CBP that the current bond doesn't adequately secure. Either way, the letter is generated automatically — it doesn't explain the underlying tariff or duty math, it just states the new required number and your deadline.
CBP's own guidance on a related insufficiency trigger — mail returned as undeliverable — states plainly what “doing nothing” leads to: “Failure to receive those notifications, or to promptly take the necessary corrective actions, will lead to the insufficiency of the continuous bond.” Once your bond flips to insufficient status in ACE, CBP will not process new entry filings against that bond number until it's corrected — cargo arriving during that window can be held at the port.
- The date printed at the top of the letter — this is day zero
- A specific compliance date or day-count stated in the letter body
- If neither is clear, call the number on the letter or email CBP's Revenue Division Surety Bonds & Accounts Team at bondquestions@cbp.dhs.gov
Have your letter in hand?
Tell us the amount and your deadline — we quote the replacement bond and flag whether you need same-day bridge coverage.
How CBP got the number in your letter
The figure isn't arbitrary — it comes straight out of CBP Directive 3510-004, and it moves faster than most importers expect.
Under CBP Directive 3510-004 (Monetary Guidelines for Setting Bond Amounts), a continuous Activity Code 1 bond's penal sum is priced at 10% of the duties, taxes, and fees you paid CBP as importer of record in the lookback period the directive uses, rounded to the nearest bracket, with a $50,000 absolute floor. That 10% figure is the same mechanism whether you're applying for a new bond or getting flagged on a sufficiency review — the review just runs the formula again against your current duty volume and compares it to what's on file.
The Activity Code 1 continuous bond formula
CBP Directive 3510-004 (Monetary Guidelines for Setting Bond Amounts): 'the bond limit of liability amount shall be fixed in multiples of $10,000 nearest to 10 percent of duties, taxes and fees paid by the importer or broker acting as importer of record during the calendar year preceding the date of the application... In no event shall the limit of liability amount of any continuous Activity Code 1 bond be less than $50,000.'
There's a second bracket most explainers miss. Once your prior-year duties cross $1,000,000, Directive 3510-004 switches the rounding increment from the nearest $10,000 to the nearest $100,000. That means a large importer whose duty bill lands just above the $1M line can see a jump in the required bond that's driven purely by which rounding bracket applies — not just by how much their duties actually grew. If your letter's number looks like a big round increase, this is often why.
None of this is guesswork on CBP's side — 19 CFR § 113.62 is the bond condition you already agreed to when you filed your continuous bond: it obligates you to deposit duties, taxes, and charges CBP demands, and (since a 2009 amendment) to comply with the Importer Security Filing rule. The Directive 3510-004 formula is simply CBP re-checking whether your penal sum is still large enough to back that promise given your current import volume.
Don't just double your old bond
The instinct when a letter arrives is to round up hard and move on — double the old bond, pad it for safety, done. That can backfire two ways. Size it below CBP's stated minimum and your application gets bounced back, burning days you don't have. Size it well above the minimum without a reason and you pay premium on penal sum you don't need, since bond premium scales with the bond amount.
The number in the letter is CBP's calculated minimum under Directive 3510-004 — you can't go lower, but you can ask your broker to show you the trailing duty total the letter is based on and decide whether to add a deliberate cushion. That cushion matters most if you know a rate increase or new tariff action is about to land on your product lines: Section 232, Section 301, and other tariff actions have been stacking on the same entries through 2025-2026 (the IEEPA-based tariffs were struck down by the Supreme Court in February 2026), which is exactly what pushes duty totals — and therefore required bond amounts — up between one sufficiency review and the next. Sizing tight to today's minimum with a known increase already in motion is how importers end up back here in six months with a second letter.
The 10% formula and $50,000/$1M brackets are .gov-verified (CBP Directive 3510-004). The tariff-stacking framing describes the general 2025-2026 duty environment, not a specific case — talk to a licensed producer about your actual exposure before choosing a cushion above CBP's stated minimum.
The termination cascade if you do nothing
What happens on each side of your deadline, and why the ordinary gap-free bond swap doesn't apply once a sufficiency letter is active.
From letter date to insufficient status
Timing is relative to the date printed at the top of your letter, not the date received
| Timing | Bond status | What CBP is doing | What you need to have done |
|---|---|---|---|
| Day 0 (date on letter) | Still sufficient | Revenue Division issues the letter after an ACE sufficiency review flags your penal sum as too low | Note the exact date at the top — that date starts your clock, not the day you open the mail |
| Your response window (15 days under 19 CFR 113.13(c); confirm the date on your letter) | Still sufficient — window to act | CBP is waiting on a replacement bond filing or a termination/replacement request from your surety | File the replacement bond application; do not let a termination go in without a replacement ready |
| Deadline date, no action filed | Flips to insufficient | ACE blocks new entry filings under the old bond number | A same-day single-transaction bond per shipment (per CBP Directive 3510-004) while the continuous replacement finishes underwriting |
| Normal bond swap (no active sufficiency letter) | N/A — different scenario | CBP can delay the "Primary Termination Date" to a "Conditional Termination Date" so the swap is gap-free | Not available on this page's scenario — see note below |
The gap-free 'Conditional Termination' option is CBP's standard accommodation for routine bond replacements. It explicitly does not apply to a bond that is the subject of an active sufficiency letter — which is exactly the situation this page covers.
CBP, 'Conditional Termination and New Bond Request Procedures': a Conditional Termination Date requires that 'the existing bond cannot be the subject of an active bond sufficiency letter issued by CBP.' Insufficiency consequence language: CBP, 'Insufficient Bonds Related to Returned Mail': 'Failure to receive those notifications, or to promptly take the necessary corrective actions, will lead to the insufficiency of the continuous bond.'
Why the gap-free swap doesn't apply to you
On a routine bond change — switching sureties, adjusting coverage, no letter involved — CBP will often let the old bond's termination land the day before the new bond takes effect, so there's zero gap. CBP's own procedure for that accommodation lists it as conditional on the existing bond not being the subject of an active sufficiency letter. Once you've received one, plan as if you will not get the seamless version — which is the entire reason the single-transaction bridge bond in the next section exists.
CBP's own three options for an inadequate bond
Directive 3510-004 doesn't just set the formula — it also spells out what a port director can do when a bond doesn't cover a shipment.
CBP Directive 3510-004 gives the district director three tools when a continuous bond doesn't adequately cover a particular shipment: (1) secure a cash deposit of the estimated duty at release, (2) require a single transaction bond for that specific entry, or (3) require that a new continuous bond in a higher amount be filed. For an importer mid-replacement, option 2 is almost always the practical choice — it covers exactly the shipments caught in the gap without a cash deposit and without waiting on the full continuous bond underwriting.
A single transaction bond is sized to that one shipment's entered value plus duties, taxes, and fees — or up to 3x entered value for restricted merchandise, including some goods under FDA, EPA, DOT, or other partner-agency admissibility requirements — with a $100 regulatory minimum under 19 CFR § 113.13. Because it's scoped to one entry rather than your full annual duty volume, it can typically be issued same-day, which is the entire point when a shipment is landing before your continuous bond replacement is active.
- A shipment is scheduled to arrive before the replacement continuous bond can be underwritten and filed
- Your surety needs one or two extra business days and your deadline is close
- You're switching sureties entirely and want zero risk of an entry clearing under a bond that's about to go insufficient
Full pricing and timing details for one-off entries live on the Customs Single Entry Bond product page. For the replacement continuous bond itself, the standard product page and formula walkthrough is at Customs Bonds.
Deadline coming up fast?
Give us the amount from your letter and we'll quote the replacement bond and, if you need it, a same-day single-transaction bridge in the same call.
The regulatory text behind your letter
Bond insufficiency is a YMYL topic with real deadlines attached — direct quotes from the controlling CBP sources so you can verify them yourself.
Official CBP Requirements
"In no event shall the limit of liability amount of any continuous Activity Code 1 bond be less than $50,000."CBP Directive 3510-004 — Monetary Guidelines for Setting Bond Amounts • CBP Directive 3510-004
Official CBP Requirements
"A Conditional Termination Date requires that "the existing bond cannot be the subject of an active bond sufficiency letter issued by CBP.""U.S. Customs and Border Protection • CBP — Conditional Termination & New Bond Request Procedures
Official CBP Requirements
"Failure to receive those notifications, or to promptly take the necessary corrective actions, will lead to the insufficiency of the continuous bond."U.S. Customs and Border Protection • CBP — Insufficient Bonds Guidance
19 CFR § 113.62 establishes the continuous bond conditions (duty payment, ISF compliance) you agreed to when the bond was filed; the sufficiency review and insufficiency-letter process that checks whether your penal sum still backs that promise is administered by CBP's Revenue Division under Directive 3510-004 and the procedural guidance quoted above — it is not itself codified in Part 113. External .gov links are rel="nofollow noopener noreferrer".
The calls about this letter all start the same way — and end differently based on one detail
Almost every call about an insufficiency letter opens with the caller reading me the new dollar figure and asking if it's a mistake. It usually isn't — it's the 10% Directive 3510-004 formula catching up to a duty bill that grew faster than the importer was tracking. The detail that actually determines how stressful the next two weeks are is whether they called the day they got the letter or the day before the deadline. Importers who call early almost always get the replacement bond filed with room to spare, no port holds, no cash deposits. Importers who call on day 12 of a 15-day window are the ones asking me about single-transaction bridge bonds at 4pm because a container is landing tomorrow.
The other pattern worth naming: importers who assume they can just let the old bond run out and switch sureties on their own schedule. That works for a routine carrier switch. It does not work once a sufficiency letter is active, because CBP's own conditional-termination accommodation — the one that lets a bond swap happen with zero coverage gap — explicitly excludes bonds under an active sufficiency letter. Nobody reads that far into CBP's procedural guidance until they're already in the gap.
This describes the general 2025-2026 calling pattern around insufficiency letters, not a specific client scenario. Surety bond decisions depend on your specific duty volume, shipment schedule, and the exact language in your letter — consult a licensed producer before acting on any bond-sizing or timing estimate.
Questions importers actually ask about this letter
Not generic customs-bond FAQs — the second-call questions specific to an insufficiency notice.
I just opened a CBP insufficient bond letter. What do I do in the next hour?
How many days do I actually have to respond to the letter?
Can I just increase my existing bond instead of buying a completely new one?
What if my new bond isn't active before the old one lapses — will shipments get stuck at the port?
Will CBP terminate my current bond automatically, or do I have to request it?
My new required amount looks like way more than double my old bond — is that normal?
Related customs bonding resources
Product pages, related guides, and tools for sizing and comparing customs bonds.
Customs Bonds: Continuous, Single Entry & ISF
Full CBP guide covering every bond type and Activity Code.
Continuous Customs Bond ($50,000 minimum)
Standard Activity Code 1 continuous bond, priced annually.
Single Entry Bond ($100 minimum bond amount, same-day)
The instrument behind the single-transaction bridge strategy above.
Continuous Customs Bond Calculator
Run your own duty total through the 10% Directive 3510-004 formula.
Customs Bond Types Compared
Single entry vs continuous vs TIB vs ISF, side by side.
Customs Bond Requirements Guide
Full importer requirements, from first bond to renewal.
Temporary Import Bond (TIB)
Different instrument, different rules — for goods leaving again.
Tariff Stacking 2026: Is Your Bond Too Small?
How Section 232 and Section 301 tariff stacking drives 2026 insufficiency letters.
Continuous vs Single Entry: The Breakeven Math
Deciding between a bridging STB and going straight to a bigger continuous bond.
How Much Is a Customs Bond?
2026 costs and formulas across every CBP bond type.
Replacement continuous bond quote
Get a quote sized to the exact figure from your CBP letter.
Eric Drummond
Licensed Surety Producer
- Nevada: License #4222379 (Property & Casualty)
All content is researched from official state and federal sources (.gov) and reviewed by surety bond specialists. Bonds are placed with Treasury-listed surety carriers; approval and pricing are determined by the issuing carrier.
Don't let the deadline pass while you're still comparing quotes
Send us the amount from your letter and we'll size the replacement correctly the first time — plus a same-day single-transaction bond if you have shipments landing in the gap.