The 39-week payment period
Maternity Allowance is paid for up to 39 weeks. That single number shapes every budget decision around a new baby, because the leave it sits alongside is longer. Employees can take up to 52 weeks of Statutory Maternity Leave. The two clocks run together but they are not the same length, and the gap between them is where many families are caught out.
39 paid weeks inside 52 weeks of leave
If you take the full 52 weeks of leave and your Maternity Allowance runs for the full 39 weeks, the final 13 weeks of leave are unpaid. GOV.UK makes this point directly on the Maternity Allowance pages: taking the full 52 weeks of Statutory Maternity Leave means the final 13 weeks will be unpaid. That is not a penalty and it is not an error in your claim. It is the design of the system: pay covers 39 weeks, leave covers 52.
The practical consequence is timing. Because the payment period is fixed at a maximum of 39 weeks, you cannot stretch it by starting later and finishing later in a way that creates extra paid weeks. What you can do is choose when the 39 weeks start, within the permitted window, and plan your spending around the unpaid tail. Some families save during pregnancy for those 13 weeks; others return to work earlier; others check whether other benefits or a partner's leave can bridge the gap. All of those are legitimate choices, but they need to be made deliberately, not discovered in week 40.
Does the period ever run shorter than 39 weeks?
Yes, in a few situations. The unpaid-work route for a spouse or civil partner's business is capped at 14 weeks, not 39. A claim that starts late can lose weeks that fall outside the backdating limit, which is three months from the start date. And if you return to work in a way that ends entitlement, or your circumstances change in a way you must report, payments can stop before 39 weeks are complete. The normal case, though, is a full 39-week run for someone who meets the eligibility test and claims in good time.
Budgeting rule of thumb
Plan on 39 weeks of Maternity Allowance, then plan separately for up to 13 further weeks with no maternity payment. If your employer offers enhanced maternity pay, a return-to-work bonus, or paid annual leave you can take at the end of leave, those change the picture; check your contract, because contractual pay sits on top of, or instead of, the statutory picture described here.
Keeping in touch days
Within the payment period you can take up to 10 keeping in touch days without affecting the amount of Maternity Allowance you receive. These are days you work for your employer while still on maternity leave, for example to attend training, a handover, or a team meeting. You must still report them, and GOV.UK lists returning to work, including keeping in touch days, among the changes you must report. Working beyond 10 keeping in touch days can affect your payment, so keep a simple record of each day you work, even a part day, and report it promptly.
What happens after the 39 weeks end?
When the payment period ends, Maternity Allowance stops. That does not end any leave you still have, and it does not require you to return to work on a particular date if your leave runs longer. If you decide not to return to work after your Maternity Allowance has ended, GOV.UK states that you do not need to report that decision. What you may need to do is check other support: Child Benefit, Universal Credit, and help with childcare costs all have their own rules, and the other benefits page explains how they interact with Maternity Allowance.
Sources: GOV.UK, Maternity Allowance: what you will get; GOV.UK, Maternity Allowance: report a change of circumstances.