The Complete Guide to Collecting Retainers Online for an Accounting Firm

Why retainers are the right first thing to move online

Most accounting firms already know the pain of the paper retainer. You send the engagement letter, ask for a deposit, and then wait. The check arrives late, or a client forgets, and the work slips before it even starts. Choosing to collect retainers online is the single change that removes that waiting period, and it fits an accounting firm better than almost any other kind of business.

The reason is simple: your engagements are planned, repeatable, and tied to a signed scope. A client already expects to pay something up front for tax season, a books cleanup, or ongoing advisory work. The only real question is how they hand you the money. When that step lives online, the deposit clears while the client is still motivated, and your team can open the file the same day the letter is signed.

What collecting a retainer online actually means

At its core, an online retainer is a payment request your client can complete from a link or a page on your site. Instead of mailing a check or reading card numbers over the phone, the client sees the amount, enters their details, and confirms. The funds route to your firm, and the transaction is recorded so you are not retyping anything later.

With a platform like Flux, the fields where a client types a card number are hosted inside origin-isolated iframes on payments.fluxpayments.com. That matters because the sensitive data never touches your firm's servers or your domain. You get the deposit and a clean record, without becoming the custodian of raw card data.

How does collecting a retainer online work, step by step?

The flow is short. First, you create a payment request for the retainer amount tied to the engagement. Second, you send the client a link, or embed a hosted field on your intake page. Third, the client pays with a card, an ACH bank transfer, or stablecoins. Fourth, the funds settle: cards in 1-2 business days, ACH in 1-3 business days, and stablecoins to your wallet instantly. Fifth, the transaction syncs to your books so the deposit is already categorized when you look.

For repeat clients, tokenization lets you keep a secure reference to a payment method without storing the actual number, so the next retainer is a one-click ask rather than a fresh data-entry chore.

Cards, ACH, or stablecoins: choosing a rail for deposits

Cards are the path of least resistance for smaller retainers. Clients trust them, they settle in 1-2 business days, and the experience is familiar. ACH suits larger deposits where a client would rather move money straight from a bank account. Stablecoins is there for clients who prefer it and settles to your wallet instantly.

Flux charges a flat 2.9% plus 30 cents per transaction, with no setup fees, monthly fees, or minimums. If your firm processes at higher volume, custom interchange-plus pricing is available. Where local surcharging rules allow, you can also pass the processing fee to the client at checkout, which some firms prefer for large engagement deposits.

Keeping retainer funds clean in your books

A retainer is usually unearned revenue until you do the work, so it needs to land somewhere you can track it as a liability and draw against it as you bill. The advantage of collecting online is that every deposit arrives with a record instead of a memory. Flux syncs transactions into QuickBooks, so the deposit, the fee, and the client reference are all there when you reconcile.

This is also where compliance quietly pays off. Because card data was captured inside Flux's hosted fields rather than your systems, your reconciliation is about matching numbers, not about defending a spreadsheet full of card details you never should have held.

Getting started without a heavy lift

You do not need to rebuild your website or sign a long contract to start. Flux has no setup fees and no contracts, so a firm can apply, drop in hosted fields or send a payment link, and begin collecting deposits. If you want to talk through how retainers map to your engagement workflow first, the team is reachable at (813) 402-8244 or sales@fluxpayments.com, and you can apply at /apply.html.