New senior engineer not working out? How to decide before probation ends

When a new hire isn't working out, don't wait for a feeling. Run a 10-working-day diagnosis, put a 30-day plan in writing, and decide before probation ends. In our judgment, that's enough time to tell a setup failure from a wrong hire. The law decides how much time you have: Germany allows up to six months of probation with two weeks' notice, the Netherlands one or two months with no notice period, and in the UK probation comes from your contract, while the unfair-dismissal qualifying period in Great Britain is due to drop from two years to six months on 1 January 2027 for most employees. This isn't legal advice, so check each point with employment counsel in your country. For more guides in this area, see Engineering management guides for CTOs and VPs of Engineering.

Is it the setup or the hire?

Start by deciding which problem you have, because the fix for each is different. In our judgment, a senior engineer who underdelivers in week three is often blocked rather than incapable, but not always, and you can tell the difference from evidence you already have.

What you see	Likely cause	First check
No pull request in the first week	Access or CI blocked, or first ticket too vague	Can they build, run tests and push today?
Same review comment on three PRs	Unwritten conventions, or not listening	Is the convention written down anywhere?
Silence instead of questions	No named person to ask, or fear of looking junior	Who did you tell them to ask?
PRs wait days for review	Your side, not theirs	Median hours from PR opened to first review
Vague or shifting first tickets	Nobody owns the scope	Could another engineer pick up the ticket cold?
Needs architecture context	The context lives in one person's head	Is there a doc, ADR or recorded walkthrough?
Strong take-home, weak on your codebase	Interview tested the wrong thing, or the codebase is hard	Did a current engineer struggle in the same area recently?

DX's analysis of developer onboarding uses time to a new hire's 10th pull request as an established ramp-up metric. It isn't a benchmark for your team, but it's a useful idea. In our judgment, a senior with no merged PR by week two or three and no blocker on your side is a signal worth acting on. Treat that as a trigger for the diagnosis, not as a verdict.

This page is about an employee. If the person was placed by a vendor, the replacement terms and the escalation path are different, and handling an underperforming staff augmentation developer covers that case.

Audit your own side in 10 working days

Before you say anything to the engineer, check what you gave them. This takes about two weeks of normal work, not a project.

Access first. Repository, CI, staging, secrets, the ticket tracker, on-call tooling. If the engineer needed more than a day to get any of them, write down which and why.

Then first tickets. Were the first three scoped so that a stranger could finish them? A senior who gets "improve the billing service" has been given a research task, not an onboarding ticket.

Then people. Is there a named buddy who answers questions the same day? Is your review turnaround under a day? Slow review on your side looks identical to slow delivery on theirs.

Finally, expectations. Did anyone write down what good looks like at 30, 60 and 90 days? If not, you can't fairly hold anyone to it yet. The checklist in the first 14 days of onboarding a contract developer works for employees too, apart from the contract-specific parts.

Last, hear their view from someone other than their lead. Skip-level meetings for engineering leaders are the cheapest way to find out whether the engineer thinks the setup is the problem. They'll often say things to a manager's manager that they won't say to their own.

If the audit turns up real gaps, fix them this week and restart the clock. If it doesn't, you have a performance question, and the next section is how to answer it without drifting.

How to decide before probation ends

It assumes you've found no major setup failure, or you've fixed it. The deadline comes first, so step 1 is the contract.

1. Fix the decision date from the contract, not from the calendar

Open the employment contract and find the last day of probation, the notice period during it, and whether it can be extended. Subtract two weeks. That's your decision date. The buffer is our judgment: in Germany it matches the two-week notice in section 622(3), while in the Netherlands there is no notice during the trial, so the buffer is just room to act. In the Netherlands, where probation is one or two months, the date arrives in week three or four, which is faster than any 30-day plan. If that's your situation, compress steps 2 to 4 into the time you have and be honest with the engineer about why.

2. Diagnose for 10 working days

Run the audit above. Keep a dated list of what you checked and what you changed. By the end you should be able to say, in one sentence each, what the engineer has shipped, what blocked them, and what you fixed on your side.

3. Put a 30-day plan in writing

Write no more than three items, each specific and measurable: what ships by when, how many review rounds are acceptable, and how a blocker gets escalated. Add a weekly checkpoint with a fixed time. Write the exit criteria on day one, so nobody argues later about what "good enough" meant. Hand the engineer the plan and ask whether the items are realistic. If they say no, listen: that's diagnostic information.

This is our judgment, not a standard. Three items is a rule of thumb, not a legal or industry number. More than three and you're writing a wish list.

4. Review at day 20 with evidence

Meet at day 20, not day 30, so there's still time to act. Bring merged PRs, tickets closed, review comments and the changes you made on your side. Compare against the plan, item by item. Decide privately beforehand what you'd need to see to confirm the hire, and whether you'd extend or re-scope if you see less.

5. Decide: confirm, extend, re-scope or part ways

Make the call at least two weeks before probation ends (our judgment, see step 1), and write down why.

Confirm if the plan items shipped and the engineer's trajectory is clear. Re-scope if the engineer is strong in one area and struggling in another: a smaller surface, or a different team, with a new 30-day plan. Extend only where the contract and local law allow it, and only with a specific reason. Part ways if the evidence shows the gap isn't setup, and the plan didn't close it.

In our judgment, re-scoping is underused and extending is overused. Extending without a changed condition just postpones the same decision with less legal protection for you and more anxiety for them.

Probation rules in Germany, the Netherlands and the UK

This is a practical summary from primary sources, not legal advice. Ask employment counsel in your country before you act.

Country	Probation	Notice during probation	Protection
Germany	Up to 6 months	2 weeks	Dismissal protection (KSchG) starts after 6 months of employment
Netherlands	1 or 2 months, agreed in writing	None	Ask counsel
Great Britain	Set by your contract	Per contract	Unfair-dismissal qualifying period: usually 2 years now, 6 months from 1 January 2027 for most employees

Germany (Probezeit)

Section 622(3) of the German Civil Code (BGB) says that during an agreed probation period, "längstens für die Dauer von sechs Monaten", employment can be ended with two weeks' notice. After probation, section 622(1) sets four weeks' notice, to the 15th or to the end of a calendar month.

Probation and dismissal protection run on separate clocks. Section 1 of the Dismissal Protection Act (KSchG) makes a dismissal invalid if it's socially unjustified, once the employment has lasted more than six months. Those two sixes coincide often, but the clocks are independent. Whether the protection applies to a small employer, and whether works council, pregnancy or disability rules affect you, are questions for counsel.

Netherlands (proeftijd)

The Dutch government's business.gov.nl page says a trial period is only valid when agreed in writing, and can never exceed two months. The limit is one month for temporary contracts of more than six months and less than two years, and for temporary contracts with no end date; two months applies to permanent contracts and to temporary contracts of two years or more. No trial period is allowed for contracts of six months or less. There is no notice period during the trial period, and you may dismiss without grounds, though the employee can ask for written grounds. Illness doesn't extend the trial or block dismissal during it. The same period applies to both parties, so the engineer can also leave immediately.

What happens after the trial ends is a question for counsel.

The practical consequence is simple. With one or two months, you decide in week three or four. Run the diagnosis in the first ten days and skip the idea of a long improvement window.

United Kingdom

In our judgment, treat probation as a contractual term and read your own contract; counsel can confirm how it interacts with the law.

What is sourced is the qualifying period for unfair dismissal. Gov.uk says employees "can usually only claim unfair dismissal if they've worked for a qualifying period. This is usually 2 years." It also says: "From 1 January 2027, most employees will be able to claim unfair dismissal after 6 months." That change is for Great Britain; GOV.UK says Northern Ireland is still usually one year. The commencement instrument is SI 2026/559, made on 26 May 2026. Its regulation 3 brings the remaining provisions of section 25 of the Employment Rights Act 2025 into force on 1 January 2027.

Which rule applies depends on the effective date of termination. Under regulation 4, a dismissal made before 1 January 2027 whose effective date of termination falls on or after that date is covered by the new six-month rule. Ask counsel about your specific case.

What to document in all three

This part is our judgment, and it applies everywhere. Keep dated expectations, the PRs, tickets and reviews you assessed, and the changes you made on your side. If a decision is ever challenged, a record that shows you gave clear targets and removed blockers is the best thing you can have.

What this means for your next senior hire

The decision in front of you is whether to confirm, extend, re-scope or part ways, but the one after that is how this person got through your hiring. If your interview was a take-home and a conversation, you tested whether they can write code in isolation. You didn't test whether they can ramp up in your codebase. Fix that loop before the next search, and a guide to vetting software developers is a place to start. For comparison, HighCircl's vetting runs four stages, run by senior engineers, and about 10% of applicants pass.

If you part ways, plan the gap in the same week. A contractor can cover the work while the permanent search runs, and a clean handover from the departing hire matters even after two months. Judgment: the cost of a short exit is smaller than the cost of keeping the wrong engineer through a second quarter.

If the exit leaves a bus-factor risk, read what to do when a key engineer resigns for a dated 30-day plan that also works for early leavers.

FAQ

What is the 30-60-90 rule for a new hire?

It's a widely used framework that sets a goal for each 30 days. For a senior engineer, our version is: at 30 days, context and first merged work; at 60 days, an owned slice of the system; at 90 days, ownership of a decision. It's a judgment framework, not a legal standard, and in the Netherlands a one-month trial period ends before day 60.

How long does it take to know a new senior engineer isn't working out?

You should see merged work and review feedback by weeks two to three, and decide at least two weeks before probation ends. That's our judgment. On a one-month Dutch trial, that means week two. The law sets the deadline: up to six months in Germany, one to two months in the Netherlands. Don't let the signal wait for the longest period the law allows.

Can you dismiss a new hire in probation without giving a reason?

In the Netherlands, business.gov.nl says you may dismiss without grounds during the trial period, with no notice. In Germany, section 622(3) BGB allows two weeks' notice during probation of up to six months; whether you need a reason depends on whether dismissal protection applies, which starts after six months under the KSchG. In the UK, it depends on the qualifying period, the effective date of termination and the contract, so ask counsel.

Does a UK employee get unfair dismissal protection after six months from 2027?

In Great Britain, yes for most employees. Gov.uk says that from 1 January 2027, most employees will be able to claim unfair dismissal after six months, and SI 2026/559 brings the remaining provisions of section 25 of the Employment Rights Act 2025 into force on that date. Until then the usual period is two years, and Northern Ireland is still usually one year. Which rule applies depends on the effective date of termination, so ask counsel about your specific case.

Should you extend probation or part ways?

Extend only if something specific changed. In the Netherlands the trial period can't exceed two months, so there's nothing to extend beyond the cap. In Germany the statutory maximum is six months, and whether an extension past it is possible is a question for counsel. If the engineer is strong in one area, re-scoping with a new 30-day plan is usually a better answer than extending the same plan. If the evidence shows the gap isn't setup, part ways before probation ends.