Raise the delay before the deadline arrives
As soon as you have good reason to believe a deadline will slip, tell the client. Waiting until you have solved every problem may feel reassuring, but it leaves them less time to adjust their own plans. You do not need perfect certainty to send an initial update. You do need a clear account of what is at risk, what you are checking, and when you will confirm the next steps.
Before you write, separate what you know from what you still need to verify. Identify the affected deliverable, its original due date, and the work remaining. Check whether the delay changes a review meeting, launch preparation, or another handoff. If the impact is not yet clear, say so and give the client a specific time for a fuller update rather than offering a date you cannot support.
Explain the cause without making excuses
Lead with the consequence for the client: which item will arrive late and what the delay may affect. Then give a brief, factual reason. A design revision that needs another round of testing calls for a different response from a delay caused by missing content or an unexpected increase in scope. The client needs enough context to assess the plan, not a detailed record of every obstacle you encountered.
Take responsibility for the work you control. If you underestimated the effort, say that you need more time to complete the agreed work to the expected standard. If you are waiting on an input, name the input and explain what can proceed meanwhile. Avoid assigning blame or treating a dependency as permission to go silent. Where the cause is shared or still uncertain, keep the description neutral and focus on the next decision.
Build a revised plan you can stand behind
Review the remaining tasks before proposing a new date. Include time for production, checking the work, client feedback, and any final changes. A revised deadline based only on the hours needed to finish your part may fail as soon as the client requests a correction. If another person must provide content or approval, make that dependency visible and explain how it affects the schedule.
Break the plan into a few useful milestones rather than replacing one distant deadline with another. For example, you might propose a draft for review, a date for consolidated feedback, and a final delivery date. State what each milestone includes so there is no confusion about whether a draft is ready to publish. Leave room for reasonable uncertainty; a realistic plan helps the client more than an optimistic promise made under pressure.
Give the client a decision, not just a warning
If there is more than one workable route, present the trade-offs plainly. The client might prefer a later delivery of the full scope, or an earlier handoff of the most important pieces with the rest to follow. For a website project, that could mean completing essential pages before optional refinements. Do not assume a partial delivery solves their problem; ask whether it would be useful and explain what would be excluded.
Make any requested action easy to identify. If you need feedback, assets, or approval to meet the revised plan, specify what you need and by when. If timing, scope, or other agreed terms may change, discuss those changes explicitly and record the resulting agreement in writing. That gives both sides a shared reference and prevents a hurried update from becoming an unclear new commitment.
Send a concise update and keep it current
A useful delay message can follow a simple order: affected deliverable, brief reason, proposed milestones, options if relevant, and the decision or input needed from the client. Use a direct subject line and put the revised date near the top. Keep the tone calm and respectful. You can acknowledge the inconvenience without filling the message with apologies that obscure the plan.
Once the client responds, confirm the agreed schedule and put its milestones into your working calendar. Send progress updates at the promised times, even if there is little to report. If a new risk appears, raise it rather than waiting for the next deadline. After delivery, note what caused the slip and whether a better estimate, earlier review, or clearer request for inputs could help you plan the next project.
