Case study · Plumbing & Heating

A new bathroom — from the first email to money in the bank.

The Krüger family wants to renovate their 30-year-old upstairs bathroom. We follow the job at Haustechnik Sommer through all eight steps — and show what NextRB Unternehmer takes care of at each one.

LSLars SommerMeister (master craftsman), owner ABAnna BergerOffice JWJonas WolfJourneyman plumber MHMia HartmannApprentice PKPetra KrügerCustomer
27days from inquiry to payment
4documents — not a single line typed twice
0paper timesheets
€4,884total job value incl. VAT, paid on time

The company, people and amounts are fictional — you’ll find them exactly like this in our „Handwerk“ (Trades) demo.

Day 1 Monday, 8:12 a.m.

The inquiry

Petra Krüger writes: Our upstairs bathroom dates from 1994. We’d like a curbless shower, a wall-hung toilet and a new washbasin. Back at the office, Anna sets her up as a lead, notes down what the family wants and books an on-site visit.

In NextRB Unternehmer
  • A lead with contact person and notes — no customer account needed yet
  • Later, one click turns the lead into a customer, and every detail carries over
haustechnik-sommer.nextrb.eu/wawi/interessenten

Interessenten

Interessent anlegen
Familie Krüger
Rosenhain 3 · 27751 DelmenhorstI-1042
Bad OG, Bj. 1994 – bodengleiche Dusche, Wand-WC, Waschtisch 60 cm. Vor-Ort-Termin Di 16 Uhr.
E-MailIn Kunden umwandeln
Day 2 Tuesday evening

Site survey and quote

Lars takes measurements on site. That evening he writes the quote: materials via the item search, working time as a labor line with a wage group — the journeyman and the Meister each have their own rate. He creates the job site at the same time; the address comes straight from the customer record.

In NextRB Unternehmer
  • Line type L for „Lohn“ (labor): hours × the wage group’s rate
  • Pick the job site while you enter the quote — it appears on the quote as the place of service
  • Sent by email as a PDF, with the labor share under § 35a EStG (the German tax credit for tradesman labor in private homes) already shown
…/wawi/angebote/AN-2026-0187
Angebot AN-2026-0187Familie Krüger
Baustelle: Bad OG, Familie Krüger · Rosenhain 3 · 27751 Delmenhorst
Waschtisch Keramik 60 cm, weiß1 Stk189,00 €
Wand-WC spülrandlos inkl. Sitz1 Stk329,00 €
Unterputz-Thermostat Dusche1 Stk412,00 €
Kupferrohr 15 mm18 m266,40 €
Arbeitszeit Geselle24 Std1.488,00 €
Abnahme, Einweisung Meister3 Std234,00 €
Anfahrt Pauschale4 ×156,00 €
Netto3.074,40 €
USt 19 %584,14 €
Angebotssumme3.658,54 €
Lohnanteil nach § 35a EStG: 2.234,82 € (inkl. USt)
Day 5 Friday, 7:42 p.m.

Accepted — signed from the couch

The quote email contains a personal link. On Friday evening Petra Krüger opens it on her phone, reviews every line item, accepts the quote and signs with her finger. A minute later the order confirmation is in her inbox — with the quote attached for comparison. On Monday, Anna sends the first progress invoice for 30%, as an e-invoice.

In NextRB Unternehmer
  • Online quote acceptance: name, signature, time and device are recorded as proof
  • The order confirmation is created and sent automatically — line items and job site carry over
  • Progress invoices from the order, as a percentage or a fixed amount — every invoice is a ZUGFeRD e-invoice (a German e-invoice format)
…/wawi/auftraege/AU-2026-0064
AngebotAN-0187
Auftragsbest.AU-0064
Abschlag30 %
Schlussfolgt
Online angenommen
Petra Krüger · Fr 19:42 · iPhoneunterschrieben
Auftragsbestätigung AU-0064 mit dem Angebot an p.krueger@beispiel.invalid gesendet
Abschlagsrechnung RE-2026-0412
30 % aus Auftrag AU-0064 · ZUGFeRD1.097,56 €
per E-Mail gesendetE-Rechnung
Day 8 Monday

Scheduling the job — together with the tiler

On the „Plantafel“ (planning board), Lars drags Jonas and Mia onto the week starting on day 15. The tiling goes to Mr. Kaya, whom he has worked with for years: Lars adds him as a participating trade and sends him the „Zeitplan-Link“ (schedule link). Mr. Kaya can see when the pre-wall installation will be in place and books Tuesday and Wednesday himself — Lars gets an email, and Jonas sees it on his phone. No phone calls, no scraps of paper.

In NextRB Unternehmer
  • Planning board: installers and other trades at a glance, with bars you simply drag
  • Schedule link for outside companies — no login, no names of your employees, no prices
  • Notes, the on-site contact and the other trades show up on the installer’s phone
…/wawi/plantafel

Plantafel · Bad OG, Familie Krüger

Tag 15 – 19
Mail an Lars: Fliesenleger (Fliesen Kaya) – neuer Termin Di – Mi über den Zeitplan-Link
Days 15–18 on site

Recorded where the work happens

In the morning Jonas opens the job site on his phone and taps „Arbeit starten“ (Start work). The clock keeps running on the server — even while the phone is in his pocket. Along the way: twelve press fittings from the van, a photo of the finished pre-wall installation and a note: Tiles behind the old toilet are loose — discussed with Mrs. Krüger. The thermostat didn’t make it onto the van, so Jonas taps „Unterbrechen für Besorgung“ (Pause for supply run), picks it up from the wholesaler and carries on 45 minutes later with „Arbeit fortsetzen“ (Resume work).

In NextRB Unternehmer
  • Time by start/stop, as hours or from–to
  • Materials from the item search — no prices on the phone
  • Trips to the wholesaler or the workshop as a separate time type
  • Photos and notes go straight to the job site in the office
‹ BaustellenJonas Wolf
Arbeitszeit läuft · seit 07:003:12:40Stopp
Zeit nachtragen
Notiz
Material
Foto
Foto · Vorwand gestellt
Besorgung 0:45 Std · Großhändler
Material · 12 Stk Pressfitting Winkel 15 mm
Notiz · Fliesen hinter dem alten WC lose
Arbeitszeit 8:30 Std · Mia Hartmann
Day 18 Thursday, 3:25 p.m.

Sign-off with a signature

The bathroom is finished. Lars walks Mrs. Krüger through it, and Jonas shows her the „Arbeitsnachweis“ (work report) on his phone: every hour, every item of material, no prices. She adds Work carried out neatly and signs with her finger. Two seconds later the PDF is in her inbox.

In NextRB Unternehmer
  • Work report with the customer’s signature, emailed instantly
  • Signed entries are locked from then on
  • No arguments over hours — the report is attached to the invoice later
ArbeitsnachweisFertig
Arbeitszeit Jonas Wolf31:00 Std
Arbeitszeit Mia Hartmann15:30 Std
Material 12 Stk Pressfitting, 18 m Kupferrohr …
Name des Unterzeichners
Petra Krüger
✓ An p.krueger@beispiel.invalid gesendet
Day 19 Friday, 9:05 a.m.

The final invoice almost writes itself

Anna opens the final invoice. On the right is the „Von der Baustelle“ (From the job site) panel: everything Jonas and Mia recorded. One click on „Übernehmen“ (Apply) — the hours land on the invoice with the right wage group, the materials with their prices. She takes out the supply run: the thermostat was missing because of a delivery delay, and Mrs. Krüger shouldn’t have to pay for that. The progress payment is deducted automatically. The invoice goes out together with the signed work report.

In NextRB Unternehmer
  • Turn the phone entries into line items with one click — each entry can be deselected individually
  • The final invoice deducts progress payments on its own
  • § 35a: the labor share is shown for the customer’s tax return
…/wawi/rechnungen/RE-2026-0451
SchlussrechnungRE-2026-0451
Material lt. Aufstellung1.296,20 €
Arbeitszeit Geselle 31 Std1.922,00 €
Arbeitszeit Azubi 15,5 Std496,00 €
Abnahme Meister 3 Std234,00 €
Anfahrt Pauschale 4 ×156,00 €
Netto4.104,20 €
USt 19 %779,80 €
Gesamt4.884,00 €
abzgl. Abschlag RE-0412−1.097,56 €
Zu zahlen3.786,44 €
Lohnanteil nach § 35a EStG: 3.341,52 € (inkl. USt)
Von der Baustelle
Übernehmen
✍ vom Kunden unterschrieben
Day 27 Saturday

Paid. And what’s left at the end.

Mrs. Krüger transfers the balance, and the open items list is empty. Anna has allocated part of the wholesaler’s invoice — the thermostat and washbasin, plus materials for another job — to the bathroom. Lars opens the „Nachkalkulation“ (job costing): a healthy margin, but 50 hours instead of 27. He hadn’t planned for Mia’s hours, and the loose tiles cost Jonas half a day. He’ll price the next bathroom with an apprentice built in.

In NextRB Unternehmer
  • Job costing per job site: estimated, recorded, invoiced — with the contribution margin
  • Allocate supplier invoices to job sites in full or in part
  • Record the payment, then export to DATEV (the accounting software most German tax advisors use) for your tax advisor at month-end
…/wawi/baustellen · Nachkalkulation

Bad OG, Familie Krüger

bezahlt
Erlös netto4.104,20 €berechnet · kalkuliert 3.074,40 €
Kosten2.587,95 €Lohn 1.736,75 · Material 412,30 · Eingangsrechnung 438,90
Deckungsbeitrag1.516,25 €▲ 36,9 % vom Erlös
Stunden50:15 Std▲ 186 % von 27:00 Std
Besorgungen 0:45 Std · Großhandelsrechnung GH-88213: 438,90 € von 612,40 € dieser Baustelle zugeordnet

What changes compared with paper slips and spreadsheets

Before

  • Timesheets reach the office crumpled on Friday — or not at all
  • Materials get forgotten and never billed
  • Quote, order and invoice are each typed up from scratch
  • Progress payments are deducted by hand, and you work out § 35a yourself
  • Arguments over hours once the invoice arrives
  • Scheduling with the tiler by phone — and in the end nobody knows what the bathroom actually earned

With NextRB Unternehmer

  • Hours, materials and photos come in from the phone while the work is being done
  • One click moves everything into the invoice — with wage group and price
  • Each document builds on the last: quote → order → progress invoice → final invoice
  • NextRB Unternehmer calculates progress payments and the labor share
  • The customer accepts the quote online and signs off on the work before the invoice goes out
  • The tiler books his own days, and job costing shows the contribution margin

Click through this case yourself.

In the „Handwerk“ demo you’ll find the Krüger family, the job site with every entry, the signed work report, the planning board and the tiler with his schedule link — no sign-up needed, just try it out.

Open the Handwerk demo Try it free