diff --git a/go/svc/invoice/main.go b/go/svc/invoice/main.go
index 11733c4..4a80441 100644
--- a/go/svc/invoice/main.go
+++ b/go/svc/invoice/main.go
@@ -95,7 +95,7 @@
 	}
 }
 
-func (s *service) invoicePDF(ctx context.Context, uid string) ([]byte, error) {
+func (s *service) invoicePDF(ctx context.Context, uid, language string) ([]byte, error) {
 	sealed, err := s.m.getSealedUid(ctx, uid)
 	if err != nil {
 		return nil, err
@@ -115,7 +115,7 @@
 			return nil, err
 		}
 
-		rendered, err = renderInvoicePDF(invoice)
+		rendered, err = renderInvoicePDF(invoice, language)
 		if err != nil {
 			return nil, err
 		}
@@ -124,7 +124,7 @@
 }
 
 func (s *service) RenderInvoice(req *pb.RenderInvoiceRequest, srv pb.Invoicer_RenderInvoiceServer) error {
-	rendered, err := s.invoicePDF(srv.Context(), req.Uid)
+	rendered, err := s.invoicePDF(srv.Context(), req.Uid, req.Language)
 	if err != nil {
 		if _, ok := status.FromError(err); ok {
 			return err
@@ -150,7 +150,11 @@
 }
 
 func (s *service) SealInvoice(ctx context.Context, req *pb.SealInvoiceRequest) (*pb.SealInvoiceResponse, error) {
-	if err := s.m.sealInvoice(ctx, req.Uid); err != nil {
+	useProformaTime := false
+	if req.DateSource == pb.SealInvoiceRequest_DATE_SOURCE_PROFORMA {
+		useProformaTime = true
+	}
+	if err := s.m.sealInvoice(ctx, req.Uid, req.Language, useProformaTime); err != nil {
 		if _, ok := status.FromError(err); ok {
 			return nil, err
 		}
diff --git a/go/svc/invoice/model.go b/go/svc/invoice/model.go
index 701807a..51fe850 100644
--- a/go/svc/invoice/model.go
+++ b/go/svc/invoice/model.go
@@ -54,7 +54,7 @@
 	return err
 }
 
-func (m *model) sealInvoice(ctx context.Context, uid string) error {
+func (m *model) sealInvoice(ctx context.Context, uid, language string, useProformaTime bool) error {
 	id, err := strconv.Atoi(uid)
 	if err != nil {
 		return status.Error(codes.InvalidArgument, "invalid uid")
@@ -81,6 +81,9 @@
 
 	`
 	sealTime := time.Now()
+	if useProformaTime {
+		sealTime = time.Unix(0, invoice.Date)
+	}
 	res, err := tx.Exec(q, id, sealTime.UnixNano())
 	if err != nil {
 		return err
@@ -101,11 +104,16 @@
 	}
 
 	invoice.State = pb.Invoice_STATE_SEALED
-	invoice.FinalUid = fmt.Sprintf("FV/%s", finalUid)
+	// TODO(q3k): this should be configurable.
+	if language == "pl" {
+		invoice.FinalUid = fmt.Sprintf("FV/%s", finalUid)
+	} else {
+		invoice.FinalUid = fmt.Sprintf("%s", finalUid)
+	}
 	invoice.Date = sealTime.UnixNano()
 	calculateInvoiceData(invoice)
 
-	pdfBlob, err := renderInvoicePDF(invoice)
+	pdfBlob, err := renderInvoicePDF(invoice, language)
 	if err != nil {
 		return err
 	}
@@ -142,7 +150,13 @@
 			?, ?
 		)
 	`
-	res, err := m.db.Exec(sql, data, time.Now().UnixNano())
+
+	t := time.Now()
+	if id.Date != 0 {
+		t = time.Unix(0, id.Date)
+	}
+
+	res, err := m.db.Exec(sql, data, t.UnixNano())
 	if err != nil {
 		return "", err
 	}
@@ -216,7 +230,7 @@
 	}
 	if s.finalUid.Valid {
 		p.State = pb.Invoice_STATE_SEALED
-		p.FinalUid = fmt.Sprintf("FV/%s", s.finalUid.String)
+		p.FinalUid = fmt.Sprintf("%s", s.finalUid.String)
 		p.Date = s.sealedTime.Int64
 	} else {
 		p.State = pb.Invoice_STATE_PROFORMA
diff --git a/go/svc/invoice/render.go b/go/svc/invoice/render.go
index 68e3472..03dcd77 100644
--- a/go/svc/invoice/render.go
+++ b/go/svc/invoice/render.go
@@ -13,18 +13,25 @@
 )
 
 var (
-	invTmpl *template.Template
+	invTmpl map[string]*template.Template
+
+	languages       = []string{"en", "pl"}
+	defaultLanguage = "en"
 )
 
 func init() {
-	a, err := templates.Asset("invoice.html")
-	if err != nil {
-		panic(err)
+	invTmpl = make(map[string]*template.Template)
+	for _, language := range languages {
+		filename := fmt.Sprintf("invoice_%s.html", language)
+		a, err := templates.Asset(filename)
+		if err != nil {
+			panic(err)
+		}
+		invTmpl[language] = template.Must(template.New(filename).Parse(string(a)))
 	}
-	invTmpl = template.Must(template.New("invoice.html").Parse(string(a)))
 }
 
-func renderInvoicePDF(i *pb.Invoice) ([]byte, error) {
+func renderInvoicePDF(i *pb.Invoice, language string) ([]byte, error) {
 	type item struct {
 		Title     string
 		UnitPrice string
@@ -95,8 +102,12 @@
 	data.Total = fmt.Sprintf(unit+"%.2f", float64(i.Total)/100)
 	data.DeliveryCharge = fmt.Sprintf(unit+"%.2f", float64(0))
 
+	if _, ok := invTmpl[language]; !ok {
+		language = defaultLanguage
+	}
+
 	var b bytes.Buffer
-	err := invTmpl.Execute(&b, &data)
+	err := invTmpl[language].Execute(&b, &data)
 	if err != nil {
 		return []byte{}, err
 	}
diff --git a/go/svc/invoice/statusz.go b/go/svc/invoice/statusz.go
index 525d61e..0a64ce4 100644
--- a/go/svc/invoice/statusz.go
+++ b/go/svc/invoice/statusz.go
@@ -50,7 +50,12 @@
 					<td>{{ index .Data.CustomerBilling 0 }}</td>
 					<td>{{ .TotalNetPretty }}</td>
 				    <td>
+						{{ if eq .State 2 }}
 						<a href="/debug/view?id={{ .Uid }}">View</a>
+						{{ else }}
+						<a href="/debug/view?id={{ .Uid }}&language=en">Preview (en)</a> |
+						<a href="/debug/view?id={{ .Uid }}&language=pl">Preview (pl)</a>
+						{{ end }}
 					</td>
 				</tr>
 			{{ end }}
@@ -90,7 +95,7 @@
 	})
 
 	m.HTTPMux().HandleFunc("/debug/view", func(w http.ResponseWriter, r *http.Request) {
-		rendered, err := s.invoicePDF(r.Context(), r.URL.Query().Get("id"))
+		rendered, err := s.invoicePDF(r.Context(), r.URL.Query().Get("id"), r.URL.Query().Get("language"))
 		if err != nil {
 			fmt.Fprintf(w, "error: %v", err)
 		}
diff --git a/go/svc/invoice/templates/invoice_en.html b/go/svc/invoice/templates/invoice_en.html
new file mode 100644
index 0000000..fb2af50
--- /dev/null
+++ b/go/svc/invoice/templates/invoice_en.html
@@ -0,0 +1,189 @@
+<!doctype html>
+<html lang="en">
+    <head>
+        <meta charset="UTF-8">
+        <title>Invoice 0001</title>
+        <link href="https://fonts.googleapis.com/css?family=Roboto:300,400,700" rel="stylesheet">
+        <style type="text/css">
+body {
+    background-color: #fff;
+    font-family: 'Roboto', sans-serif;
+    font-size: 1em;
+
+    padding: 2em;
+}
+ul {
+    list-style: none;
+    padding: 0;
+}
+ul li {
+    margin-bottom: 0.2em;
+}
+
+@page {
+  size: A4;
+  margin: 0;
+}
+div.rhs {
+    float: right;
+    width: 50%;
+    text-align: right;
+}
+div.lhs {
+    float: left;
+    text-align: left;
+    width: 50%;
+    min-height: 35em;
+}
+div.metadata {
+    margin-top: 2em;
+}
+div.invoicee {
+    margin-top: 9em;
+}
+h1 {
+    font-size: 1.5em;
+    margin: 0;
+    text-transform: uppercase;
+}
+h2 {
+    font-size: 1.2em;
+    margin: 0;
+}
+table.items {
+    text-align: right;
+    border-spacing: 0px;
+    border-collapse: collapse;
+    border: 0;
+    width: 100%;
+}
+table.items td,th {
+    border: 1px solid black;
+}
+table.items tr:first-child {
+    background-color: #eee;
+    color: #111;
+    padding: 0.8em;
+    text-align: left;
+}
+table.items td {
+    background-color: #fff;
+}
+table.items td,th {
+    padding: 0.5em 1em 0.5em 1em;
+}
+td.lhead {
+    border: 0 !important;
+    text-align: right;
+    text-transform: uppercase;
+    background: rgba(0, 0, 0, 0) !important;
+}
+div.bgtext {
+    z-index: -10;
+    position: absolute;
+    top: 140mm;
+    left: 0;
+    width: 100%;
+}
+div.bgtext div {
+    text-align: center;
+    font-size: 10em;
+    color: #ddd;
+    -webkit-transform: rotate(-45deg);
+    text-transform: uppercase;
+}
+        </style>
+    </head>
+    <body>
+        {{ if .Proforma }}
+        <div class="bgtext"><div>Proforma</div></div>
+        {{ end }}
+        <div class="rhs">
+            <div class="invoicer">
+                <ul>
+                    {{ range $i, $e := .InvoicerBilling }}
+                    {{ if eq $i 0 }}
+                    <li><b>{{ $e }}</b></li>
+                    {{ else }}
+                    <li>{{ $e }}</li>
+                    {{ end }}
+                    {{ end }}
+                    {{ if .InvoicerCompanyNumber }}
+                    <li>{{ .InvoicerCompanyNumber }}</li>
+                    {{ end }}
+                    <li><b>Tax Number:</b> {{ .InvoicerVAT }}</li>
+                </ul>
+            </div>
+            <div class="metadata">
+                <ul>
+                    <li><b>Invoice number:</b> {{ .InvoiceNumber }}</li>
+                    <li><b>Date:</b> {{ .Date.Format "2006/01/02" }}</li>
+                    <li><b>Due date:</b> {{ .DueDate.Format "2006/01/02" }}</li>
+                    <li><b>IBAN:</b> {{ .IBAN }}</li>
+                    <li><b>SWIFT/BIC:</b> {{ .SWIFT }}</li>
+                </ul>
+            </div>
+        </div>
+        <div class="lhs">
+            <div class="invoicee">
+                {{ if .Proforma }}
+                <h1>Proforma Invoice</h1>
+                {{ else }}
+                <h1>VAT Invoice</h1>
+                {{ end }}
+                <ul>
+                    {{ range $i, $e := .InvoiceeBilling }}
+                    {{ if eq $i 0 }}
+                    <li><b>{{ $e }}</b></li>
+                    {{ else }}
+                    <li>{{ $e }}</li>
+                    {{ end }}
+                    {{ end }}
+                    {{ if .USCustomer }}
+                    <li>EIN: {{ .InvoiceeVAT }}</li>
+                    <li><b>(VAT zero rate)</b></li>
+                    {{ else }}
+                    <li><b>NIP:</b> {{ .InvoiceeVAT }}</li>
+                    {{ end }}
+
+                    {{ if .ReverseVAT }}
+                    <li><b>(reverse charge applies)</b></li>
+                    {{ end }}
+                </ul>
+            </div>
+        </div>
+        <div style="clear: both; height: 1em;"></div>
+        <table class="items">
+            <tr>
+                <th style="width: 60%;">Description</th>
+                <th>Price<br />(ex. VAT)</th>
+                <th>Qty</th>
+                <th>VAT rate</th>
+                <th>Total<br />(net)</th>
+                <th>Total<br />(inc. VAT)</th>
+            </tr>
+            {{ range .Items }}
+            <tr>
+                <td style="text-align: left;">{{ .Title }}</td>
+                <td>{{ .UnitPrice }}</td>
+                <td>{{ .Qty }}</td>
+                <td>{{ .VATRate }}</td>
+                <td>{{ .TotalNet }}</td>
+                <td>{{ .Total }}</td>
+            </tr>
+            {{ end }}
+            <tr>
+                <td colspan="5" class="lhead">Subtotal without VAT</td>
+                <td>{{ .TotalNet }}</td>
+            </tr>
+            <tr>
+                <td colspan="5" class="lhead">VAT Total{{ if .ReverseVAT }} (reverse charge applies){{ end }} {{ if .USCustomer }}(VAT zero rate){{ end }}</td>
+                <td>{{ .VATTotal }}</td>
+            </tr>
+            <tr>
+                <td colspan="5" class="lhead"><b>Total</b></td>
+                <td><b>{{ .Total }}</b></td>
+            </tr>
+        </table>
+    </body>
+</html>
diff --git a/go/svc/invoice/templates/invoice.html b/go/svc/invoice/templates/invoice_pl.html
similarity index 100%
rename from go/svc/invoice/templates/invoice.html
rename to go/svc/invoice/templates/invoice_pl.html
diff --git a/proto/invoice/invoice.proto b/proto/invoice/invoice.proto
index 187e358..a5c6a84 100644
--- a/proto/invoice/invoice.proto
+++ b/proto/invoice/invoice.proto
@@ -29,10 +29,13 @@
     string customer_vat_id = 6;
     bool reverse_vat = 7;
     bool us_customer = 11;
+    // Optional, if not given the proforma will be created with the current time.
+    int64 date = 14;
     int64 days_due = 8;
     string iban = 9;
     string swift = 10;
     string unit = 13;
+    // Next tag: 15
 }
 
 message Invoice {
@@ -74,6 +77,7 @@
 
 message RenderInvoiceRequest {
     string uid = 1;
+    string language = 2;
 }
 
 message RenderInvoiceResponse {
@@ -82,6 +86,12 @@
 
 message SealInvoiceRequest {
     string uid = 1;
+    enum DateSource {
+        DATE_SOURCE_NOW = 0;
+        DATE_SOURCE_PROFORMA = 1;
+    }
+    DateSource date_source = 2;
+    string language = 3;
 }
 
 message SealInvoiceResponse {